Gero created his ultimate creation, Cell. Cell was programmed from the DNA of Gohan, Goku, Vegeta, Piccolo, etc. Cell's main purpose was to absorb androids #17 & #18. Cell came from the future into this world to absorb the androids because Trunks had killed them in the future. Cell had to absorb the androids to reach his ultimate form, and as he knew the Z fighters main attacks (kamehameha, energy disc, solar flare, etc.), stopping him proved almost impossible. He absorbed #17 first, and reached his semi-perfect form, and then Vegeta let him absorb #18 in order for him to reach his perfect form. After he beat Trunks and Vegeta, he issued a tournament called the Cell Games because he wanted to face Goku. Cell was disappointed when Goku forfeited the match and let Gohan take his place. Underestimating Gohan's true power proved to be a mistake, and when Cell had his “cell juniors” attack the Z fighters, and crushed Android #16's head, Gohan unleashed his full power and went super saiyan 2. Even when Cell went to his super perfect form, he still couldn't beat Gohan and Gohan punched android #18 out of him, so he self-destructed. Goku teleported him to king kai's planet and he blew up, killing Goku & king kai. Cell somehow regenerated from a single cell and came back to Earth. During a furious battle of kamehamehas, Gohan finally won, and Cell was wiped off the face of the planet.
Attacks: kamehameha, ultimate kamehameha, solar flare, special beam cannon, teleport(later), energy disc, self-destruct, mult-form, regenerate, freeza beam, energy burst, flame cannon, Cell junior attack, super ki blast.
Power level at beginning of DBZ: 45,000,000
Power level at end of DBZ: 300,000,000
Class: andriod