Android 21 created by Dr. Gero. He was completed in Future Trunks' timeline. Cell killed Future Trunks, stole his time machine, and travelled back to the timeline we know of to absorb Androids 17 and 18 to reach perfect form. Trunks warned them about the arrival of #17 and #18, but things didn't go exactly as predicted. Soon, the artificial humans were no longer the greatest danger. To fight Cell, Piccolo merged with Kame-Sama, which increased dramatically his skills. Piccolo could have beaten Cell in his 2nd. evolutionary state, but he got away after using the sunlight to temporarily blind the near-by fighters.

Cell wasn't seen again until he found #17, who was fighting Piccolo, and absorbed him. Later, he absorbed #18 too and Piccolo was now no match for Cell. Vegeta had the chance to kill Cell when he was in his 3rd. evolutionary state, but he was tricked by Cell into letting him reach his perfect form (he would be a real match, then). It was thanks to Trunks and his time capsule that Cell was able to find them and evolve to Perfect Cell.

Trunks tried to destroy Cell before he could reach this state, but Vegeta stopped him. Basically, Gohan killed Cell. After Goku gave up in the middle of the fight with Cell, designating his son as the next challenger, Gohan stood still, unwilling to fight, explaining that only when extremely angry could he be a match for Cell. The reptile-like creature then sent miniature versions of itself to attack Gohan's friends. Gohan eventually got so furious that he turned into SSJ2.

He killed the Junior Cells effortlessly and beat up Cell until he coughed out #18 and returned to his third evolutionary state. Cell, in a last effort, starts expanding and Goku is forced to take him away with Teleportation. Had he exploded, Earth would have been destroyed, so Goku uses the Teleportation technique to teleport Cell to King Kai’s planet, killing himself, killing King Kai and his pets, but unfortunately not killing Cell.