Daleks are the mutated descendents of the Kaleds from the planet Skaro. Created by the mad Kaled scientist Davros, the Daleks were engineered to feel only hate. The Daleks are the enemies of the Doctor and his race, the Time Lords.
The Daleks originated on the war-torn planet of Skaro after it was ravaged by a Thousand Year War between the Thals and the Kaleds, who were the Dalek's earliest recorded ancestors. Their government and military were exclusively ran by the head of the Kaled Science Division, a crippled prophet of wisdom named Davros. Originally, Davros presented the idea of the Daleks as a new means of transportation for the Kaled people, after the next stage of their evolution. However, Davros' true intentions with the Daleks was to create an army of soldiers robbed from all forms of emotion but hate. Davros was convinced that the only sure way for the Kaled people to survive was through absolute conquest, and he saw no more fitting way for conquest than the extermination of everything non-Dalek.
The Kaleds eventually caught onto Davros' plans with the help of the Fourth Doctor, who was visiting Skaro at that time period in an attempt to sabotage the birth of Davros' new race. Meanwhile, Davros was escorted into the Thal city by one of his loyalists, and there he gave his opposing the forces a chemical formula capable of melting away the protective shell over the last remaining Kaled city: making them vulnerable to the Thalan weapon missile already armed to destroy them. He assured the Thalan rulers that he was purely doing this just to end this war, and cared not who the victor was any longer... However in fact he was really lying to his loyalists, who he told was aiding him in a trick to safeguard the Kaleds from the Thal's weapons.
When the Thals launched their missile, they successfully destroyed the entire Kaled race, saving only those who were still underground inside Davros' science division. The POW's the Thals had left, the Doctor's companions being among them, were set free. And the two companions convinced their newly freed comrades to help them get back to the Kaled bunkers, to help aid the Doctor's quest to destroy the Daleks before they are created.
When Davros returned to his headquarters above the freshly laid ruins of the Kaled city, he shifted more of his attention towards the Doctor, who was revealed to Davros to be from the future with means of technology and knowledge far beyond anything Skaro's ever considered possible... But more importantly; the Doctor knew of every way the Dalek's ever lost in battle. Davros was overjoyed to learn that not only does his "children" survive, but they even conquer and exterminate worlds from other galaxies he didn't even realized existed yet. Davros decided it would be best to use the Doctor's "inferior" concept of a morality against him, by wiring him to a lie detector, and his companions to a pair of torturing devices. Davros' plan succeeded, he found out every last flaw in every last battle strategy the Daleks would ever use, and he intended to have the recordings he took from the Doctor and plant them into the memory banks of every last Dalek that he plans to build. The Doctor eventually found a way out of that jam, and destroyed the recordings Davros took of him with a Dalek gun that was not yet assembled into a live casting yet.
The Doctor and his companions then escaped from Davros and his children before they were able to catch up to him. However he did ultimately fail in his mission of preventing the birth of the Daleks. When put up to the task to annihilate all the pre-alternated Dalek lifeforms, he felt it was not in his power to end an entire civilization no matter how wicked they may become... He figured that even through the Daleks that some good may have been brought to the universe, even if it may only be as subtle as two enemy races allying with each other to fight off the Daleks for their lives...
After The Doctor and his companions fled the remains of the Kaled City, a group of natives of Skarans given the name "Mutos" and allied Thals detonated a series of bombs to destroy all the Daleks inside Davros' research building. However, they were somehow unsuccessful in causing the building to collapse. They only succeeded in trapping Davros and his Daleks inside there, for what the Doctor estimated to be a good thousand years.
Inside those walls, one Dalek gave orders to his comrades to begin the process of more Daleks to aid them. Davros made a desperate attempt to get his children to obey him, but they stated to them that Daleks were not designed to see any life superior to them that was not Dalek... That he was not only stripped of his will over them but now registered as an enemy. Davros made one desperate move to detonate the Dalek's self destruct button, but they exterminated him right before he was able to end them.
The Daleks then took all that time they were forced into giving to plan, and eventually they freed themselves and expanded into the universal terror they were destined to be.
Destiny of The Daleks
After 90 years after the events on Skaro in "Genesis of The Daleks", the Supreme Dalek of a freshly built Dalek Empire revives their creator, Davros, to help their empire battle a deadly plague the Movellans set loose upon the Daleks that only infects their kind. Davros uses this to his advantage and seeks out a way to get his creations to obey him again, so he secretly begins experiments on the test subjects first before actually trying to seek out a cure.
The Doctor, now at his fifth regeneration, arrives at the mothership of the Daleks and intends to kill Davros. However, he could not do so indirectly but he does reveal Davros' true intentions to his captors. In a state of panic, Davros sets loose the Movellan virus upon the ship and kills every Dalek on board, and then escapes through an escape pod shortly before the Dalek ship is destroyed. However, it was implied that Davros himself somehow became infected with this virus, and he reportedly died once again... Along with the rest of the Dalek race.
The Master's Trial and Skaro's Rebirth
During the Seventh Doctor's regeneration back on Skaro, The Master was being put on trial by the Daleks and was sentenced to death. Master contacted the Doctor and requested that his remains would be returned to Gallifrey after his execution. It was never confirmed if Skaro at this point in time was either revived somehow, or if the trial was taken in some other point in time there.
During Master's execution, he then absorbed a Deathworm to cheat death, and he used the TARDIS to travel to 1999, where he stole the body of an ambulance driver called "Bruce", and planned to transfer his spirit into the Doctor's body, usurping it.
During this newly established Dalek Empire, it was foretold that the Daleks have mastered time / space travel just as the Time-Lords did. And shortly after they began reaching out to other galaxies to achieve their right as the only living things worthy of ruling the universe, nothing. This is where the Great Time War began, between the Daleks and Gallifreyans. It was never confirmed how exactly it began, and only the Doctor knows really how it ended.
In the first episode of the unofficial revamp of the Daleks in the new series; A lone Dalek crashed to Earth in the 1950's. It survived falling through the time vortex, but was so hot that it burned for three days. It was passed through auctions until it came into the hands of Henry Van Statton. A billionaire who invented the Internet that has a immense museum of Alien artifacts in a underground bunker in Utah. Van Statton spent years torturing the Dalek in hopes of hearing it speak.
Decades after the Dalek fell to Earth, The Doctor picked up it's faint distress call (he didn't know it was a Dalek distress signal) and went to investigate. When the Doctor found out it was a Dalek(at the time believing that it was the last of the race) pleaded with Van Statton to kill it. Van Statton though ignored the Doctors warnings. When Rose touched the Dalek it was able to absorb the time radiation from her and restored it's system to full power. It then broke out of it's prison(by breaking a billion digit code in seconds) downloaded the internet and drained most of the power from the western part of the U.S. It then carried on it's primary mission of eradicating all non Dalek life. While the lone Dalek was killing all of its opposition, it couldn't bring itself to kill Rose. It had also seemingly gained a connection to her and begun to develop feelings. In the end believing that it was alone and loathing itself for now being tainted and impure, the Dalek chose to destroy himself.
The Parting of Ways
Near the end of the ninth Doctor's incarnation, it was revealed the the lone Dalek was not the only survivor of the Dalek Empire, but a ship with the Dalek Emperor survived as well. He claimed that he rebuilt the entire Dalek race from scrap matter he's collected from human corpses on Earth, and even though he didn't specify how he tells that he cleansed the humanity from the harvestings he's collected to create pure Dalek life. He exclaimed that by forging life out of mere dust, that he was the Dalek's God... And he was anticipating on creating a "Heaven on Earth" for his species by purging the world in fire and exterminating everything already living there.
This massive new Dalek armada was on it's way to invading Earth (However, in a few thousand years into the future, where the Doctor and company were residing.) The Doctor during this time forced his companion Rose Tyler to take the TARDIS back to her own home and time period, so she would not have to die fighting the Daleks. She immediately began searching through every means that she could to go back to the Doctor afterwards, willing to risk her life for the chance to try to save his.
At this time, it was revealed that the Doctor had only one choice left to kill all the Daleks for good: by sending a wave throughout the perimeter of the Dalek armada to attack the Delta brain waves of every last one of them, killing them all. However, as the Dalek "God" revealed to Captain Jack Harkness, this would also exterminate everyone on Earth as well. The Doctor felt that it was more important for one civilization to die than let the Daleks kill numberless others, and the Dalek God was pleased to see him considering become just as evil as his race was.
Rose Tyler eventually found her way back to save the Doctor seconds before his extermination, by opening up the heart of the TARDIS and absorbing the time Vortex inside. When she came back to the time period the Doctor was in, she was able to use her all-powerful new energy source to wipe out the entire Dalek armada by de-bonding every last molecule holding them and their ships together. The Doctor then had to absorb the Time Vortex out of her before her mind overheated and she was killed, and this lead to the Doctor's 10th regeneration shortly after.
The Cult of Skaro
The Cult of Skaro is a group of four Daleks (Sec, Caan, Thay, and Jast) that had the job of imagining new ways of killing. They survived the time war in a void ship and attempted to open the Genesis Ark. The Genesis Ark was a prison ship created by the Time Lords and it had held millions of Daleks. While the Cult was able to open the Ark, the Doctor was able to open a portal into the void(an empty space between two universes) that sucked all of the Daleks in. The Cult though was able to survive by doing a 'emergency time shift'.
Daleks in Manhatten
The time hift placed them in 1930's New York, during the building of the Empire State Building. The Cult though was weakened from the time shift and had to resort to hiding in the bowels of the new building. They captured humans and turned them into human-pig like hybrids. The hybrids had amplified strength, were blindly loyal to the Cult and had a limited life span. Sec's master plan was to turn the human race into a new hybrid race containing Dalek D.N.A. Sec first attempted the procedure on himself becoming the first of the hybrid race. The other three members of the cult though had doubts about Sec's plan. They ultimately betrayed Sec and eventually killed him. In the ensuing battle the Dalek's Jast and Thay are killed, but Caan manages to escape through an emergancy timeshift.
The Stolen Earth/Journey's End
Dalek Caan had flown through the Time War and saved the Dalek Empire but had gone insane from the Journey. The Daleks stole a 27 of Planets throughout Space and Time to use as satellite to direct a "Reality Bomb" capable of dismantling creation itself, with Davros overseeing the project as the head scientist, second to only the new Dalek Emperor himself. The Doctor stopped Davros with the help of his companion Rose, a half-Time Lord half-Human clone of himself, and company after disrupting the Dalek's motor capabilities and setting the Dalek space station to self destruct. It was here that Dalek Caan explained that he already saw this coming, and just played his hand to help... And that it was the Doctor's destiny to end all things Dalek in the universe. The Doctor agreed with this himself, and fled into the TARDIS with the others. He even offered to help save Davros from another demise, but the mad Kaled refused and named the Doctor "The Ender of Worlds" before the TARDIS escaped. It appeared that Davros was killed once again in the Dalek base along with the entire Dalek army, however since his death was not shown on screen it is very likely that Davros will make a return eventually.
Victory of The Daleks
Early into the 11th Doctor's life, he encounters the Daleks who were serving as allies with Winston Churchill during WWII. The allied British army was convinced by the Daleks that they were created by one of their scientists after having a mysterious revelation with the idea of them, however the Doctor was not convinced by their ruse and tried tempting one Dalek to break character while attacking it with a pipe. However, when he does this, he inadvertently gives the Daleks what they were looking for; a "testimony" that they were indeed Daleks. Their "creator", as it turns out, was actually built by them to convince the allies the Daleks were tools for to aid their victory against the Nazis. This Dalek-puppet was equipped with a progenitor device, that the Daleks saved from their recent destruction. This device contained pure Dalek-DNA - just not the verification that it was in fact Dalek until the Doctor says it's so.
After needing no more help from the humans they teleported back to their ship that was based behind the moon. There, they were able to genetically engineer a new pure race of Daleks that were planted into colored castings and much more dangerous arms. The new pure Daleks' first act of birth was to exterminate the inferior models, which let so happen willingly. The new Daleks were able to disintegrate them in a single blast.
Afterwards, the new Daleks intended to bomb Earth after the Doctor issued an attack on their ship. The Doctor hesitated in doing so, but he did while allowing the Daleks a chance to escape to save Earth. But as a cruel jester against their Time-Lord enemy, the Daleks activated the bomb anyways, but the Doctor was able to disarm it through the designated "creator" of the Daleks, who needed to be convinced that he was in fact a human instead of a bomb.
The Pandorica Opens / The Big Bang
These new Daleks were later seen after allying themselves with the Doctor's other enemies at the Pandorica opening, which may have either implied they have some concern over the universe than their earlier counterparts who planned on destroying creation, or they feel that they would go out of their way and resist killing an entire army full of "inferior" species just to see the Doctor be beaten for good.
Afterwards, during the collapse of reality that the Doctor was trying to keep from destroying creation; a single new Dalek emerges, a Stone Dalek. This one was kept in the same museum the Pandorica was held in for over two thousand years, and resembled the most recent brand of Dalek, but completely molded out of stone.
After the time where Amy Pond's younger self released her elder self from the prison, this Dalek began recharging itself when reawakened.
This Dalek would go on to chase the Doctor and company throughout the museum, and even successfully landed a what seemed to be a kill-shot on the Doctor. However, it's life was ended when it made the mistake of assuming the Doctor's "associate" River Song would show mercy on him, as his shield density was critically weakened due to it not being fully recharged. River Song shot this Dalek dead in it's eyestock, after first making it plea for mercy.
The Dalek Invasion of Earth
Mission to the Unknown
The Dalek Master Plan
Power of the Daleks
Evil of the Daleks
Day of the Daleks
Frontier in Space
Planet of the Daleks
Death to the Daleks
Genisis of the Daleks
Destiny of the Daleks
The Five Doctors
Resurrection of the Daleks
Revelation of the Daleks
Rememberance of the Daleks
Bad Wolf / The Parting of the Ways
Army of Ghosts / Doomsday
Daleks in Manhattan / Evolution of the Daleks
The Stolen Earth / Journey's End
The Waters of Mars
Victory of the Daleks
The Pandorica Opens / The Big Bang
The Daleks have fought many wars in there time and have invaded and conquered many planets and many of their conflicts have left big marks on the history archives.
The Daleks have armor that was forged by a metal only found naturally on Skaro called Dalekanium. Dalekanium was durable enough to resist attacks from bullets and most lasers and bombs, which makes the Daleks very hard to defeat - especially with the heavy shielding they have on top of it. It's been mentioned that every aspect of Dalek-casting is designed for either protecting the mutated Skaran inside or to kill.
For most models of the species, the Achilles's heel of the Daleks is their eyestocks. Without them, they are unable to see and have to rely on the vague readings they pick up inside their armor, which can only detect living beings but not locate them.
The movable appendages of the Dalek include the head and torso, which only moves from side to side, the eyestock, which moves up and down on the head, and the stiff metal arm and Dalek gun, which have limited free movement around half of a spherical base.
The Dalek gun was removable in the original Dalek models, and were able to fire beams that could light up an entire room and possibly exterminate multiple targets at once... However as they advanced their weapon's range grew much more thinner, however provided to be much more lethal in combat.
The current "pure race" models of the Daleks are capable of firing death rays potent enough to disintegrate the previous models of their race, and their shells appear to be much larger than the others, and even reflect off of the earlier versions of Dalek-kind along with some modified features.