Who's the most powerful sith?

Ok, I know that not everyone is up to date with the Sith of the Old Republic, but come on. Palpatine is NOT the strongest sith!! Lord Vitiate, the Sith Emperor, is the strongest sith; he consumed most of the Sith of the time, increasing his power far beyond that of any other sith. Palpatine doesn't even come close!!!!

@JediXMan

@ShootingNova

Palpatine was the most powerful Sith during his time.The Old republic is set before.

Nova and Xman will be able to give you better answers.

This has been done far too often. Canon has answered this already. So I'm just going to take stuff from posts already made.

@ShootingNova said:

This question has been answered by canon numerous times:

Darth Sidious, in all. Master of the seven lightsaber forms, is a master of them ambidextrously, moves at near-relativistic speeds, creates wormholes that rip through time-space continuum and destroy fleets/planets/moons, drains an entire planet with a population of 20 billion, mind-wiped an entire world's worth of people, and is immune to Nihilus' drain, has arguably the most powerful Force Lightning, has studied from numerous holocrons including Naga Sadow's, Bane's (which holds all of Revan's knowledge), Freedon Nadd's, even some Jedi ones, and much more. He is also a master of Essence Transfer and is the only one who involuntarily uses it.

He has been stated to be the most powerful Sith Lord ever numerous times:

Yoda went after Palpatine in the empty Senate chamber, but could not defeat the most powerful Sith Lord in history.

--Taken from The New Essential Chronology

Darth Sidious proved to be the grim culmination of a thousand years of Sith philosophy and teachings.

--Taken from Jedi vs Sith: The Essential Guide to the Force

When the Sith finally emerged from a thousand years of watching and waiting, they numbered—in accordance with the tradition set down by Darth Bane—only two. The most powerful of these was Darth Sidious, an ice-cold, diabolically calculating genius equipped with the strength of the dark side of the Force, as well as an enormous wealth of Sith artifacts, equipment, and knowledge.

--Taken from The Dark Side Sourcebook

And then there was Palpatine, of course: he was beyond power. He showed nothing of what might be within. Though seen with the eyes of the dark side itself, Palpatine was an event horizon. Beneath his entirely ordinary surface was absolute, perfect nothingness. Darkness beyond darkness. A black hole of the Force.

--Taken from Revenge of the Sith

Plagueis made a soothing gesture and explained in great detail what had taken place. Concluding, he said, "He threatened, too, to place you out of reach."
All the while Plagueis spoke, Palpatine was storming through circles on the narrow path, shaking his head in anger and balling his fists. "He can't do this!" he snarled. He hasn't the right! I won't allow it!"
Palpatine's fury buffeted Plagueis. Blossoms growing along the sides of the pathway folded in on themselves, and their pollinators began to buzz in agitation. FourDee reacted, as well, wobbling on its feet, as if in the grip of a powerful electromagnet. Had this human truly been born of flesh-and-blood parents? Plagueis asked himself. When, in fact, he seemed sprung from nature itself. Was the Force so strong in him that it had concealed itself?

--Taken from Darth Plagueis

Palpatine has spent decades studying the most arcane and esoteric Jedi disciplines. It is believed that he has mastered nearly all the known powers, previously unknown powers, and devises new ones at his pleasure.

--Taken from the Dark Empire Sourcebook

And many other times also.

@daviddavid7 said:

Ok, I know that not everyone is up to date with the Sith of the Old Republic, but come on. Palpatine is NOT the strongest sith!! Lord Vitiate, the Sith Emperor, is the strongest sith; he consumed most of the Sith of the time, increasing his power far beyond that of any other sith. Palpatine doesn't even come close!!!!

And he did so via a ritual. He has dominated the minds of a hundred, but guess what? Palpatine has enslaved the minds of nearly twenty billion (the entire population of Byss):

What better lure for multitudes than Byss's siren call of beauty and peace? Once there, their wills are destroyed by the Emperor and his Adepts, and replaced with an illusion of tranquility as they blissfully surrender their life energy to sustain the Emperor.

--Taken from Dark Empire Sourcebook

Vitiate required a ritual that took both time and a hundred other Sith Lords to drain a planet.

Palpatine has drained an entire planet while travelling around the galaxy, doing whatever he wants to do, and without the need of paying attention to the matter. He did so of his own power, his own sheer power:

Throughout the worlds submissive to the Empire, Byss is renowned as a paradise, whose siren call multitudes to willingly apply for emigration to its shores. Once there, wrapped in the power of the dark side, the immigrants become completely submissive, their life energy forever enslaved to the mind that would devour a galaxy.

--Taken from the Dark Empire endnotes

Vitiate required a ritual to create storms on Dromund Kaas.

Palpatine's mere anger creates a Weather Storm, even though he is visually holding it back:

Reeling, Ferus stood next to Vader as the Emperor approached them. Clouds had rolled in like a great gray carpet; a storm was brewing. The thickness of the air and the coming storm seemed to give a hard change to the atmosphere.

Ferus felt the blast of the Emperor's fury, though he remained calm. Palpatine came straight to Vader.

-- Taken from Last of the Jedi: Master of Deception

Unless he gathers his strength for his Force Storms (Lightning variant), Vitiate's lightning is painfully pathetic:

Revan intercepted the bolt with the blade of his lightsaber, though the impact stopped his charge dead in its tracks.

The Emperor unleashed three more bolts in quick succession. Revan batted the first aside with his lightsaber, ducked the second, then deflected the third back at its source.

It struck the Emperor in the chest, sending him sliding several meters back on the floor.

-- Taken from The Old Republic: Revan

While the power of Palpatine's lightning is shown to be capable of bending Windu's lightsaber (yes, Palpatine stopped only to convince Anakin to go to the Dark Side):

Lightning blasted the clouds above, and lightning blasted from Palpatine's hands, and Mace didn't have time to comprehend what Palpatine was talking about; he had time only to slip back into Vaapad and angle his blade to catch the forking arcs of pure, dazzling hatred that clawed toward him. Because Vaapad is more than a fighting style. It is a state of mind: a channel for darkness. Power passed into him and out again without touching him. And the circuit completed itself: the lightning reflected back to its source.

Palpatine still made no move to defend himself from Skywalker; instead he ramped up the lightning bursting from his hands, bending the fountain of Mace's blade back toward the Korun Master's face.

Mace's blade bent so close to his face that he was choking on ozone. "Anakin, he's too strong for me—"

This was beyond Vaapad; he had no strength left to fight against his own blade.

--Taken from Revenge of the Sith

Palpatine's Lightning has killed beings before:

Garrbo V'Droz almost dropped his glow rod when it shined off a face he recognized in one of the chambers. There was a grim smile on its face. The green-haired occupant of the chamber was someone with whom Garrbo V'Droz was intimately familiar: his brother, the construction foreman.

Whirling on his patron, he whimpered, "What is the meaning of this?" Emperor Palpatine smiled and said simply, "It means that you and I are the only ones left who know the way through the labyrinth to my...home for treasures too valuable even for my museum above. And soon, it will just be me," the Emperor grinned horribly, as Garrbo V'Droz cowered.

"Don't worry, my friend," hissed the dark figure, gesturing grandly at a vacant spot in the chamber, "you shall have a place of honor here. You've earned it."

Palpatine raised his hands, preparing to strike, and then, allowing himself a final moment to savor the fear in his victim, added, "And if 1 ever need your services again, I will not hesitate to clone you."

V'Droz cringed as the Emperor threw vicious bolts of lightning from his hands and ensured that the galaxy's finest architect was forever a part of his last, greatest work.

--Taken from The Thrawn Trilogy Sourcebook (His Finest Work) (credit to Silver2467)

"I need him alive!" Skywalker shouted. "I need him to save Padme!"

Mace thought blankly, Why? And moved his lightsaber toward the fallen Chancellor. Before he could follow through on his stroke, a sudden arc of blue plasma sheared through his wrist and his hand tumbled away with his lightsaber still in it and Palpatine roared back to his feet and lightning speared from the Sith Lord's hands and without his blade to catch it, the power of Palpatine's hate struck him full-on.

He had been so intent on Palpatine's shatterpoint that he'd never thought to look for Anakin's. Dark lightning blasted away his universe. He fell forever.

--Taken from Revenge of the Sith

We can see Vitiate having mildly impressive feats prior to any training in the Force. Palpatine's feats, prior to having any formal training in the Force, are markedly superior:

Prior to receiving any training in the Force, Palpatine hurls his father around a cabin, strangles his mother, distorts a bulkhead, and murders his siblings with the Force.

Once more Sidious allowed his memories to unfold, and he relived the crimethe event, as he had at last come to think of it. His father's limp and blooded body. The smashed skulls of the bodyguards. His hands clenched around his mother's slender throat—but not really, only in his mind, strangling her with his thoughts. The lifeless forms of his siblings, slumped here and there...

--Taken from Darth Plagueis

Prior to receiving any training, Palpatine is so powerful in the Force that Plagueis cannot scan him and is so powerful in the Force it literally conceals itself within him:

Palpatine’s fury buffeted Plagueis. Blossoms growing along the sides of the pathway folded in on themselves, and their pollinators began to buzz in agitation. FourDee reacted, as well, wobbling on its feet, as if in the grip of a powerful electromagnet. Had this human truly been born of flesh-and-blood parents? Plagueis asked himself. When, in fact, he seemed sprung from nature itself. Was the Force so strong in him that it had concealed itself?

--Taken from Darth Plagueis

Palpatine is the only one who can, by his own power, create Wormholes (which have ripped through the space-time continuum, transported beings over significant distances, obliterated fleets, and annihilated the surfaces of planets and moons):

Palpatine is regarded as a Black Hole of the Force:

Now the scene below subtly altered, though to the physical eye there was no change. Powered by the dark side, Dooku's perception took the measure of those below him with exhilarating precision.
Kenobi was luminous, a transparent being, a window onto a sunlit meadow of the Force.
Skywalker was a storm cloud, flickering with dangerous lightning, building the rotation that threatens a tornado.
And then there was Palpatine, of course: he was beyond power. He showed nothing of what might be within. Though seen with the eyes of the dark side itself, Palpatine was an event horizon. Beneath his entirely ordinary surface was absolute, perfect nothingness. Darkness beyond darkness.
A black hole of the Force.

--Taken from Revenge of the Sith

Which is much, much more impressive than anything Vitiate has been considered to be.

Palpatine has mastered all Dark Side powers and techniques, and created his own ones at leisure:

Palpatine has spent decades studying the most arcane and esoteric Jedi disciplines. It is believed that he has mastered nearly all the known powers, previously unknown powers, and devises new ones at his pleasure.

--Taken from Dark Empire Sourcebook

Which Vitiate has not done.

Additionally, Vitiate requires both relics and trinkets to bolster his own power, yet still Palpatine outclasses him in power, profusely.

There is your answer.

@YourNeighborhoodComicGeek said:

@JediXMan

@ShootingNova

Yo Nova... See even YNCG knows you're the successor of Silver...

@ssejllenrad: Dude, are you going to stalk me and post this kind of stuff on every SW thread?

@ShootingNova: Naaaah... Just the ones I stumble into... :D

@ssejllenrad: Which somehow happens to be almost all of them. Demon.

@ShootingNova: And thats why you, Nova, are the G.O.A.T.......perhaps....

@KnightRise: And now you come in as well........ how many demons must surround me whenever I post?

@ShootingNova: Your demons are directly proportional to the amount of your awesome posts.. :D

@ShootingNova: Your fault for dropping the knowledge nuke. Such ownage attracts our kind. As we scuttle gingerly around the rumble, subtle shouts of Vaapad are silenced, misguided points on Exar Kunn hushed away like noisey children. My bretheren @ssejllenrad knows. It happens to any king. Bask in it.

@ssejllenrad said:

@ShootingNova: Your demons are directly proportional to the amount of your awesome posts.. :D

Well then, I guess I won't post anymore :D

@KnightRise: My fault? My fault? How is it my fault? It's Ssejllenrad's fault for starting this Silver Jr. mess in the first place.

@ShootingNova: Don't point your finger at me SJR... Nyehehe! Peace... Ok, fine, you're not Silver Junior.... You're JXM and Silver's equal... :D

@ssejllenrad: I...... how...... what........ THAT IS EVEN WORSE!

@ShootingNova: Let JXM decide that... :D... On a side-note... WHERE THE HELL IS SILVER!?!?!?!?!

@ssejllenrad: I reserve the right to judge that........ and I judge it unworthy!

Anyways, Silver isn't interested in returning to the Battle forums. Thank the trolls.

@ShootingNova: YOU WERE THE CHOSEN ONE!!! {Ewan McGregor voice}

@KnightRise: (Dooku laugh) A bold claim!

@mrdecepticonleader said:

Palpatine was the most powerful Sith during his time.The Old republic is set before.

Nova and Xman will be able to give you better answers.

Well, Palpatine is also the most powerful Sith Lord of all time.

@ShootingNova:

And thats why I say you know more than me......or whatever I said

du.ub

@superstay: Oh no! Another demon!

@ShootingNova:

Sorry it took so long to comment back but......dõ¡ôb.....huh??? LOL

d?_?b

@superstay: LOL.

@ShootingNova:

......LOL

dõ¡ôb

@ssejllenrad said:

@YourNeighborhoodComicGeek said:

@JediXMan

@ShootingNova

Yo Nova... See even YNCG knows you're the successor of Silver...

I actually just couldn't remember Silver's username. His numbers are very hard to remember. ShootingNova is close though.

@YourNeighborhoodComicGeek: LOL, it's 2467.

I'd say Vader, but since he is the "Chosen One" it wouldn't be fair...

So I would have to say Palpatine. Make no mistake, they both possessed great minds along with great power, but it was Palpatine who succeeded where Vitiate failed. Vitiate could have easily infiltrated the Republic and hid his power amongst the Jedi until the time was right to strike, but his obsession with consuming all life to his benefit blinded him. Plus, Palpatine is powerful in manipulation. If he were alive during pre-Clone wars time, Vitiate would have been just as expendable as Plagueis and Dooku were.

Vader imagined the power that could be his if he crushed Palpatine and established his own rule over the Empire. But first, he would need his own apprentice. By himself, he could not hope to defeat the most powerful Sith Lord the galaxy had ever known.

--Taken from Vader: The Ultimate Guide

Yoda went after Palpatine in the empty Senate chamber, but could not defeat the most powerful Sith Lord in history.

--Taken from The New Essential Chronology

The Sith have waited millennium for the birth of one who is powerful enough to return them from hiding. Darth Sidious is that one—the Sith's revenge on the Jedi order for having nearly eradicated the practitioners of the dark side of the Force.

--Taken from The Complete Visual Dictionary
 

The Sith Order, in hiding for a millennium, had awaited the birth of one who was powerful enough to return the Order to prominence. Darth Sidious was the fulfillment of that prophecy, capable of exacting the Sith's revenge on the Jedi for having nearly eradicated the practitioners of the dark side of the Force.

--Taken from The Complete Star Wars Encyclopedia

Darth Sidious proved to be the grim culmination of a thousand years of Sith philosophy and teachings.

--Taken from Jedi vs Sith: The Essential Guide to the Force

When the Sith finally emerged from a thousand years of watching and waiting, they numbered—in accordance with the tradition set down by Darth Bane—only two. The most powerful of these was Darth Sidious, an ice-cold, diabolically calculating genius equipped with the strength of the dark side of the Force, as well as an enormous wealth of Sith artifacts, equipment, and knowledge.

--Taken from The Dark Side Sourcebook

In truth, Palpatine was well versed in the ways of the Force, having been apprentice to Darth Plagueis the Wise, a Sith Lord who was a master of arcane and unnatural knowledge. In true Sith tradition, Palpatine murdered his Master upon receiving the skill and ability to do so.

--Taken from The Complete Star Wars Encyclopedia

Sidious served for many decades as the apprentice of Darth Plagueis, learning diligently at the feet of his Master. Once he possessed all of Plagueis' secrets, he retired him.

--Taken from Heritage of the Sith

"My own Master, Darth Plagueis, made the grave error of teaching me too much, at which point he became unnecessary."

--Taken from Jedi vs Sith: The Essential Guide to the Force

Unknown to the Rebels, the Emperor had already laid the groundwork for the perpetual rule of his New Order. He had turned a Jedi into his new dark apprentice, the terrifying Darth Vader. Vader himself trained apprentices. And the Emperor created a corps of loyal, Force-skilled minions to maintain his rule. Most powerful of all, of course, was the Emperor himself.

--Taken from The Dark Side Sourcebook

Inside the spacious interior of the Galactic Senate chamber, Yoda challenged the Emperor. The two engaged in a spectacular duel—a contest between the most powerful practitioners of the Force’s light and dark sides.

--Taken from The Complete Star Wars Encyclopedia

It quickly became clear to Luke that this decrepit and seemingly defenseless old man was masterfully adept in the ways of the Dark Side of the Force. Indeed, as Vader had warned, the Emperor had become the Dark Side's most powerful expression.

--Taken from the Dark Empire endnotes

Even Ulic Qel-Droma would be envious of Palpatine. He had succeeded where all others had failed in taming the Dark Side.

--Taken from Dark Empire Sourcebook

Sidious knew that his own powers had increased tenfold over the decades, but he couldn’t be certain he had learned all of Plagueis’s secrets—“his sorcerer’s ways,” as the Sun Guards referred to them—including the ability to prevent beings from dying.

--Taken from Darth Plagueis

A tremor took hold of the planet.
Sprung from death, it unleashed itself in a powerful wave, at once burrowing deep into the world’s core and radiating through its saccharine atmosphere to shake the stars themselves. At the quake’s epicenter stood Sidious, one elegant hand vised on the burnished sill of an expansive translucency, a vessel filled suddenly to bursting, the Force so strong within him that he feared he might disappear into it, never to return. But the moment didn’t constitute an ending so much as a true beginning, long overdue; it was less a transformation than an intensification—a gravitic shift.
A welter of voices, near and far, present and from eons past, drowned his thoughts. Raised in praise, the voices proclaimed his reign and cheered the inauguration of a new order. Yellow eyes lifted to the night sky, he saw the trembling stars flare, and in the depth of his being he felt the power of the dark side anoint him.
Slowly, almost reluctantly, he came back to himself, his gaze settling on his manicured hands. Returned to the present, he took note of his rapid breathing, while behind him the room labored to restore order. Air scrubbers hummed—costly wall tapestries undulating in the summoned breeze. Prized carpets sealed their fibers against the spread of spilled fluids. The droid shuffled in obvious confliction. Sidious pivoted to take in the disarray: antique furniture overturned; framed artwork askew. As if a whirlwind had swept through. And facedown on the floor lay a statue of Yanjon, one of four law-giving sages of Dwartii.
A piece Sidious had secretly coveted.
Also sprawled there, Plagueis: his slender limbs splayed and elongated head turned to one side. Dressed in finery, as for a night on the town.
And now dead.
Or was he?
Uncertainty rippled through Sidious, rage returning to his eyes. A tremor of his own making, or one of forewarning? Was it possible that the wily Muun had deceived him? Had Plagueis unlocked the key to immortality, and survived after all? Never mind that it would constitute a petty move for one so wise—for one who had professed to place the Grand Plan above all else. Had Plagueis become ensnared in a self-spun web of jealousy and possessiveness, victim of his own engineering, his own foibles?
If he hadn’t been concerned for his own safety, Sidious might have pitied him. Wary of approaching the corpse of his former Master, he called on the Force to roll the aged Muun over onto his back. From that angle Plagueis looked almost as he had when Sidious first met him, decades earlier: smooth, hairless cranium; humped nose, with its bridge flattened as if from a shock-ball blow and its sharp tip pressed almost to his upper lip; jutting lower jaw; sunken eyes still brimming with menace—a physical characteristic rarely encountered in a Muun. But then Plagueis had never been an ordinary Muun, nor an ordinary being of any sort.
Sidious took care, still reaching out with the Force. On closer inspection, he saw that Plagueis’s already cyanotic flesh was smoothing out, his features relaxing.
Faintly aware of the whir of air scrubbers and sounds of the outside world infiltrating the luxurious suite, he continued the vigil; then, in relief, he pulled himself up to his full height and let out his breath. This was no Sith trick. Not an instance of feigning death, but one of succumbing to its cold embrace. The being who had guided him to power was gone.
Wry amusement narrowed his eyes.
The Muun might have lived another hundred years unchanged. He might have lived forever had he succeeded fully in his quest. But in the end—though he could save others from death—he had failed to save himself.
A sense of supreme accomplishment puffed Sidious’s chest, and his thoughts unreeled.
Well, then, that wasn’t nearly as bad as we thought it might be...
Rarely did events play out as imagined, in any case. The order of future events was transient. In the same way that the past was reconfigured by selective memory, future events, too, were moving targets. One could only act on instinct, grab hold of an intuited perfect moment, and spring into action. One heartbeat late and the universe would have recomposed itself, no imposition of will sufficient to forestall the currents. One could only observe and react. Surprise was the element absent from any periodic table. A keystone element; a missing ingredient. The means by which the Force amused itself. A reminder to all sentient beings that some secrets could never be unlocked.
Confident that the will of the dark side had been done, he returned to the suite’s window wall. Two beings in a galaxy of countless trillions, but what had transpired in the suite would affect the lives of all of them. Already the galaxy had been shaped by the birth of one, and henceforth would be reshaped by the death of the other. But had the change been felt and recognized elsewhere? Were his sworn enemies aware that the Force had shifted irrevocably? Would it be enough to rouse them from self-righteousness? He hoped not. For now the work of vengeance could begin in earnest.
His eyes sought and found an ascending constellation of stars, one of power and consequence new to the sky, though soon to be overwhelmed by dawn’s first light. Low in the sky over the flatlands, visible only to those who knew where and how to look, it ushered in a bold future. To some the stars and planets might seem to be moving as ever, destined to align in configurations calculated long before their fiery births. But in fact the heavens had been perturbed, tugged by dark matter into novel alignments. In his mouth, Sidious tasted the tang of blood; in his chest, he felt the monster rising, emerging from shadowy depths and contorting his aspect into something fearsome just short of revealing itself to the world.
The dark side had made him its property, and now he made the dark side his.
Breathless, not from exertion but from the sudden inspiration of power, he let go of the sill and allowed the monster to writhe through his body like an unbroken beast of range or prairie.
Had the Force ever been so strong in anyone?
Sidious had never learned how Plagueis’s own Master had met his end. Had he died at Plagueis’s hand? Had Plagueis, too, experienced a similar exultation on becoming a sole Sith Lord? Had the beast of the end time risen then to peek at the world it was to inhabit, knowing its release was imminent?

--Taken from Darth Plagueis

Resurrected in a youthful clone body, Palpatine does not reveal himself immediately. Studying the dark side of the Force to become more powerful, his education results in three manifestos: The Book of Anger, The Weakness of Inferiors, and The Creation of Monsters.

--Taken from The Ultimate Visual Guide

Palpatine knew precisely why the Empire couldn’t last without his dread power: he had designed it that way. No one ever suspected how much he relied on the Dark Side of the Force. He shaped those of his government by using the Force against them. He used it to control his fleets and to drive his soldiers on to victory. He used it to destroy his enemies from a distance and learn of conspiracies against him. Without it, there was no way the Empire could endure, as he had designed it. The Dark Side flowed through him like some primordial ichor and was the key to all his power.
Soon he was ready to strike. Fully healed and in greater control of the Dark Side than ever, he finally acted to end the Mutiny.

--Taken from Dark Empire Sourcebook

Now the scene below subtly altered, though to the physical eye there was no change. Powered by the dark side, Dooku's perception took the measure of those below him with exhilarating precision.
Kenobi was luminous, a transparent being, a window onto a sunlit meadow of the Force.
Skywalker was a storm cloud, flickering with dangerous lightning, building the rotation that threatens a tornado.
And then there was Palpatine, of course: he was beyond power. He showed nothing of what might be within. Though seen with the eyes of the dark side itself, Palpatine was an event horizon. Beneath his entirely ordinary surface was absolute, perfect nothingness. Darkness beyond darkness.
A black hole of the Force.

--Taken from Revenge of the Sith

The key to Luke's turning is the moment when he and Leia realize the Emperor is no longer defined by his physical form, but has become achaotic nexus of dark energies that swell and burst open the fabric of space, tearing apart everything in the vicinity, human and machine.

--Taken from the Dark Empire endnotes

Any unusual localization, or vergence, of dark side Force energy. These strange locales emanated the dark side of the Force, and were considered focal points of power for dark side users. As such, they were often guarded by Jedi Knights to prevent their discovery and exploitation. Known dark side nexuses included the twisted tree-cave on Dagobah, Halagad Ventor's hermitage on Trinta, and a "stain" of dark side energy that hovered over Endor following the defeat of the Emperor.

--Taken from The Complete Star Wars Encyclopedia

Plagueis made a soothing gesture and explained in great detail what had taken place. Concluding, he said, "He threatened, too, to place you out of reach."
All the while Plagueis spoke, Palpatine was storming through circles on the narrow path, shaking his head in anger and balling his fists. "He can't do this!" he snarled. He hasn't the right! I won't allow it!" 
Palpatine's fury buffeted Plagueis. Blossoms growing along the sides of the pathway folded in on themselves, and their pollinators began to buzz in agitation. FourDee reacted, as well, wobbling on its feet, as if in the grip of a powerful electromagnet. Had this human truly been born of flesh-and-blood parents? Plagueis asked himself. When, in fact, he seemed sprung from nature itself. Was the Force so strong in him that it had concealed itself?

--Taken from Darth Plagueis

Outside, the wind picked up another notch, shrieking and groaning among the eleven chimneys as if to announce the arrival of a hideous guest. Dooku's comm console chimed. He glanced over, expecting the daily report from General Grievous, or perhaps a message from Asajj Ventress. He reached over to open the channel, ecognized the digital signature of the incoming transmission, jabbed the channel open, and snapped to his feet. "You called, my Master?" 
The hologrammic projector on his desk sprang to life, and the wavering form of Darth Sidious regarded him. As always the picture was oozy and unclear, as if light itself were uneasy in the presence of the Lord of the Sith. Dark robes, purple shadows—a patch of skin, pale and mottled under his hooded cloak like a fungus growing under a rotten log. From under heavy lids the Master's eyes, snake-cold and serpent-wise, regarded him. 
"What would you have of me, Master?" 
"From you? Everything, of course." Darth Sidious sounded amused. "There was a time when I wasn't sure if you would be able to overcome that...independent streak of yours. After all, you were born to one of the wealthiest families in the galaxy, with gifts and abilities far, far greater than any amount of wealth could bestow. Your understanding is deep; your will, adamant. Is it any wonder you should be proud? Why, how could it be otherwise?" 
Dooku said, "I have always served you well and faithfully, my Master." 
"You have. But you must admit, your spirit was not made for fidelity. After all, a man who will not bow to the Jedi Council, or even Master Yoda...I wondered if perhaps loyalty was too mean, too confining a thing to ask from so great a being as yourself." 
Dooku tried to smile. "The war progresses well. Our plans are on schedule. I have dealt out your deaths, your schemes, your betrayals. I have paid for your war with my time, my riches, my friends, and my honor." 
"Holding nothing back?" Sidious asked lightly. 
"Nothing. I swear it." 
"Excellent," Darth Sidious said. "Yoda came to the Chancellor's office this morning. He is going on a very special mission. Top secret." He laughed, a harsh sound like the bark of a crow. The wind rose again, shrieking around the mansion like a creature in torment. "When he arrives, Dooku...see that you treat him as he deserves." 
Darth Sidious laughed. Dooku wanted to laugh along, but couldn't quite manage it before his Master cut the connection and disappeared. 
 
Dooku paced his office. With the end of Sidious' call, the storm had slackened, and the shrieking wind outside now only sobbed quietly under the gables of Château Malreaux. 

--Taken from Yoda: Dark Rendezvous

"But I was also overwhelmed by the knowledge that Vader was not only Luke's father, but mine, too. My memories raced to my first encounter with Vader. It was during my first trip to Coruscant, when I'd accompanied my father—that is, Bail Organa—to a reception for the Emperor. In hindsight, I'm surprised I was allowed to go, as it exposed me to both the Emperor and Vader. Granted, I'd never demonstrated any Force powers at that point, so perhaps Bail Organa thought it was relatively safe. I never knew anyone who guarded his secrets as well as Bail Organa.
The reception was at the Imperial Palace. As things turned out, it seems neither Sith Lord sensed anything about my true identity, for if they had, surely they would have done something. That's not to say their powers were weak. I'd meant to confront Palpatine and tell him what I thought of his xenophobic Empire, but as he approached me in the reception line, I was struck numb with fear. I remember thinking it was as if he were pitch-black inside. Vader loomed behind him like a malevolent shadow, and there was no doubt in my mind that if I had found the courage to speak my mind to the Emperor, Vader would have killed me on the spot."

--Taken from Jedi vs Sith: The Essential Guide to the Force

Palpatine has spent decades studying the most arcane and esoteric Jedi disciplines. It is believed that he has mastered nearly all the known powers, previously unknown powers, and devises new ones at his pleasure.

--Taken from Dark Empire Sourcebook 

Feats:

• Creating Force Storms capable of destroying fleets of ships and devastating the surfaces of planets
• Surviving as a spirit whenever his body is killed and traveling as a spirit across lightyears of space
• Making the planet Byss a dark side nexus
• Siphoning the life energies of the nearly 20 billion inhabitants on Byss
• Telepathically subjugating the wills of nearly 20 billion beings on Byss, erasing the memories of millions on Coruscant, and inducing fear into thousands of Jedi across the galaxy
• Projecting Force Lightning capable of scorching Sithspawn to ash, burning people to skeletons, and contorting lightsaber blades
• Causing the Force to become imbalanced to blind the Jedi's perceptions
• Hiding his Force sensitivity from the most powerful Jedi in the Order
• Perceiving events and eventualities throughout the galaxy
• Altering the tides of battles by influencing armies and fleets
• Controlling midi-chlorians to sustain life
• Moving his lightsaber too fast to be seen by Jedi who can react to lightning bolts and ships flying at sublight speeds

This has been discussed before already:

http://www.comicvine.com/forums/battles/7/all-out-fight-who-is-the-most-powerful-sith-ever/547875/