Dragon Ball Z
Cell is the ultimate creation of a scientist named Dr. Gero. Cell was cloned from the collected DNA samples the Z fighters of Earth, along with some from Nappa and Freeza and King Cold. Since Cell possessed traits from other DBZ characters, he was called "perfect warrior". In his timeline (separate from the canon timeline), Android's 17 and 18 had been destroyed and he could not achieve his goal - perfection. He took Trunks' time machine and went to a time where the androids still existed. Cell's existence is first hinted at when Future Trunks, Son Gohan and Bulma discovered Cell's discarded exoskeleton in a forest near a time machine. At this time, Cell starts to absorb humans to get even stronger. Cell is first seen and confronted by Piccolo, who soon learns the android's history of time travel as well his plans to absorb Androids 17 and 18.
Cell disappears until he manages to track Piccolo down to where he was fighting Android 17. Here, Cell easily brushes off Piccolo but is evenly matched with Android 16. By utilizing his agility and speed advantage over the bulkier android, Cell manages to absorb Android 17 and become Semi-Perfect. In this form, he confronts Android 16 and badly damages him. Cell would then go after #18 before being stopped by Tenshinhan. After he dispatches the human Z Fighter, the android is suddenly confronted by a newly-turned-Super Saiyan Vegeta.
After realizing that he could not beat Vegeta in this form, Cell uses Vegeta's Saiyan pride to trick him into letting him absorb Android 18. Little did Vegeta know that Cell's new form was more that what Vegeta's Ascended Super Saiyan form could handle. After he absorbed #18, he fought Vegeta again proving his theory on his Perfect Form. Vegeta was no match for Cell, forcing Trunks to step in to save his father.
Trunks turned to Ascended Super like Vegeta but powered up to a level that lacked speed and made up for it in power. He could actually match Cell in combat, but his bulky muscles prevented him from truly utilizing the strength advantage he had over Vegeta's Ascended Super Saiyan form. Cell, disappointed at the Saiyans' display of power, abruptly ends the fight and tells Trunks about a tournament that he will host to test his new found power called the Cell Games. He allows Trunks to live and tell the other Z warriors about this tournament and allows ten days for them to prepare. Cell makes this announcement to the world via news station so the strongest fighters in the world can come challenge him, and meet him in the ring that he created.
During the Cell games, Cell and Goku fight the first match. Surprisingly, Goku surrenders to Cell and tells him that he couldn't win. He concedes the match to his son Gohan, but Gohan is shocked to hear this. Gohan fails to defeat Cell, but Cell knows about Gohan's latent power and seeks to draw it out by any means necessary. Thus, he creates the deviants known as Cell Jr's and sends them after Gohan's friends. After Cell destroys Android 16 and crushes his head, this unlocks Gohan true power within, fueled with rage and Gohan turns into Super Saiyan 2. Gohan kills all the Cell Jr's with ease and fights Cell after. At first, Cell thinks it wouldn't make any difference, but soon realizes that he is fighting a losing battle and gets serious, but to no avail. Cell turns uses his power-weighted form to fight Gohan, but this lowers Cell's speed, a crucial mistake. Gohan easily defeats Cell in this form and Cell regurgitates out Android 18, turning him back into his second form. Cell then turns to drastic measures.
After Cell loses his perfect form, he turns to self-destructing himself to take the Earth and the Z-warriors with him. No one attacks Cell because if they did, Cell would self-destruct. Goku goes to Gohan and tells him to take care of Chi-Chi for him and goes to Cell. He places a hand on Cell and unexpectedly teleports to Kaio-Sama's world. Cell then self-destructs and destroys the small world and taking everyone there with him, including Goku. After the self-destruction, a small part of Cell survives and regenerates into Cell again, but this time Cell is back to his Perfect Form and he has achieved his Super Perfect Form, making him stronger than before. He teleports back to Earth to fight the Z-warriors once again, especially Gohan.
Cell arrives back to fight Gohan and shortly after, this time far more powerful than before, and shoots through Trunks with a beam, throwing Vegeta into a paternal rage. The Saiyan Prince attacks Cell, but is easily overwhelmed. Cell almost murders Vegeta when Gohan intervenes by using his own body to block the attack. It damages Gohan's arm and leaves him with one arm to use. Cell gets ready to destroy the Earth by charging up a kamehameha, which he claims is strong enough to destroy the entire solar system, and fires it at Gohan. Gohan uses a Kamehameha blast with his one arm and gets into a beam struggle. Cell starts to overpower Gohan when just before Gohan was about to give Goku talks to Gohan through Kaio-Sama and tells Gohan to let his power explode and not give up. Cell gets ready to overpower Gohan when suddenly he gets hit by a small chi blast from Vegeta and gets distracted. Goku tell Gohan to use his full power and Gohan unleashes it to the Kamehameha beam struggle. Cell is caught off guard and is completely overwhelmed, obliterating him to oblivion, thus ending his existence on Earth.
Dragon Ball GT
In this saga, the people sent to Hell are set loose into Earth after a portal between Hell and Earth was opened by Hell Android 17 and Earth Android 17. Goku goes to Hell after being lured in and gets trapped in Hell. He then encounters Cell and Freeza. Goku fights Cell and Freeza, but doesn't fight seriously. Cell manages to blind Goku and absorbs Goku for a few seconds. Cell gets a burst of power, but Goku manages to get out immediately from the absorption by climbing through the tail of Cell. Goku then takes tests and freezes both Cell and Freeza by a ice machine from his test. Cell is accidentally shattered by Goku along with Freeza.
Powers and Abilities
Cell is the last android created by Dr. Gero and the most powerful to date. He is a combination of genetic engineering and mechanical advancement that allowed him to be superior to his android brethren. In his first form Cell made it his mission to absorb the life force of as many people has he could. By the time he confronted Androids 17 and 18 he has already surpassed them in strength. After absorbing 17 Cell enters his semi-perfect form and has a massive upgrade in strength. Once he absorbs both androids he becomes the most powerful person on the planet at that time. Since Gero used the cells of the Z-Fighters to create Cell he gained their respective powers and abilities as well. After Freeza came to Earth, Dr. Gero got a sample of his blood as well and Cell was infused with his techniques as well as Freeza's
Cell Juniors - Likely a variation of King Piccolo's ability to create Namkeian like monsters, Cell can create blue miniature versions of himself to attack his foes. The juniors are as power as Cell himself though considerably less durable. They have access to every attack Cell does.
Death Beam - Taken from Freeza, Cell fires a small beam from his index finger with the intention to pierce through a target. He kills Future Trunks with this move.
Energy Shield - Taken from the Androids, Cell can erect an energy barrier around his body for added defense or as a quick way to repulse an enemy.
Eye Lasers - Taken from Freeza and Piccolo, Cell can fire a quick and precise blast rom his eyes to nullify other energy attacks or stun his enemy.
Galick Gun - Taken from Vegeta, Cell used this against Vegeta himself, but it had no effect since he used in in his Semi-Perfect Form.
Kamehameha Wave - Taken from Goku, Krillin, and Yamcha. This is Cell's most used attack.
Hell Bazooka - A combo attack used in conjunction with Freeza, they trap a target inside a cage of yellow energy and then plunge it into the deepest parts of Hell.
Homing Destructo Disk - Taken from Freeza, Cell is able to mentally control two purple destructo disks and have them home in on and track a target.
Instant Transmission - Taken from Goku after he self-destructed, Cell can instantly teleport himself to any location he can sense.
Life Force Absorption - Cell can use his tail to absorb the life force of a person using one of two methods. 1st method has Cell stabbing this target with the stinger of his tail and absorbing the organic matter leaving only the clothes behind as evidence. 2nd method is to open the stinger of his tail and fully engulf his target absorbing their body directly into Cell's own. Th last method was developed to absorb Androids 17 and 18 since there power comes from mechanical enhancement.
Multi-Form - Taken from Tien, Cell is able to split his body into at most four seperate entities to overwhelm his opponent through numbers. This attack splits his strength and skill into four as well.
Regeneration - Taken from Piccolo, Cell can regenerate his body as long as there is something left to start from. He was able to regenerate his entire upper body from just his legs and even formed a completely new body from a single cell from his head.
Special Beam Cannon - Taken from Piccolo, Cell gathers energy into his two fingertips and fires a beam designed to drill through a target.
Spirit Bomb - A video game exclusive power taken from Goku. Cell can bring together a massive amount of negative energy from the people of Earth and use it to form a large, green energy ball.
Solar Flare - Taken from Tien, Cell is able to flash a bright light to temporarily blind his enemies.
Super Explosive Wave - Cell can release a large amount of Energy to decimate a local area.
Telekinesis - Taken from Freeza, Cell can move objects with his mind. He uses this to create his ring for the Cell Tournament.
Telepathy - Taken from Freeza, Tien, and Piccolo, Cell is able to communicate via telepathy
Tri-Beam - Taken from Tien, Cell cups both of his hands together and fires a large square beam from his hands that uses life force.