Baby

Baby is character who appears in some of DevilArtemis' Cell Vs videos.

Originating from Dragon Ball GT, Baby is parasitic life-form created by the extinct Tuffle race to conquer the universe and kill the Saiyans. Taking over the bodies of multiple people and brainwashing them, he ultimately took control of Vegeta, thus possessing the "strongest body in the universe" in his own words.

Background
Long ago, The Tuffles, a very peaceful, technologically advanced race hailing from Planet Plant, were forced to share their planet with a very primitive, barbaric race known as the Saiyans after their home planet Sadala was destroyed from unknown circumstances. At first both races lived peacefully, but after a while, the Saiyans grew tired of their filthy lifestyles (as well as allegedly being treated like slaves) and went to war with the Tuffles.

After 10 years of warfare, the Saiyans ultimately turned out the victors, thanks to a full moon that appeared once every 100 years, which transformed them into giant apes, leaving most of the Tuffles extinct. The survivors of the war ended up creating parasitic life-forms which they infused with the Tuffle-King's DNA and sent them out into space, with their goal of getting revenge on the Saiyans, with Baby himself being one of them.

In Age 740, the grown up Baby manufactures Dr. Myuu in order to gather the resurrection energy he needs to obtain a powerful body. Baby programs Myuu with the method of developing Machine Mutants, and production began on Luud, M-2, and the others. Seemingly created as a "last resort" by the demented Machine Mutant scientist. As his name implies, Baby is highly immature and is prone to fits of rage and panic, as well as not taking his battles seriously. It is also implied that "Baby" was not his original name, or at least that this is not what he was intended to be dubbed, as Baby does not initially recognized the title and begins to dislike it.

Nearly sixty years after the extinction of the Tuffles, Baby goes to Earth, the adoptive home for the surviving Saiyans, to exact his revenge. Over the span of two days, Baby brainwashes everyone on Earth (except Piccolo, Majin Buu, Uub and Hercule) and takes over Vegeta's body, mutating it to the point that he barely resembles the Saiyan prince. It took Goku gaining the power of Super Saiyan 4 to defeat Baby and end his plans.

Perfect Cell Vs Baby Vegeta, Baby Cooler, and Baby Broly
Baby, having taken over Vegeta's body, suddenly appeared in the Cell's Arena, much to the confusion of Cell and Kermit, intending to infect and convert them to his army. Cell makes the mistake of not taking Baby seriously, which proved to be his undoing, as Baby proceeded to infect Cooler, Broly, and finally Cell himself. Kermit, lacking the raw strength to fight against Baby, was forced to seek help from Mr. Popo, who suddenly appeared in the battlefield, beat up Baby's newest bodies, and freed everyone, likely forcing Baby to flee.

Perfect Cell Vs Budget Increase Super Baby Vegeta
A while after, Baby, having somehow gained the power of Budget Increase, quickly travelled to the Cell Games Arena, intent on revenge against Cell and Kermit. He begins charging up his famous attack the Revenge Death Ball, and both Cell and Kermit (or whom he thought was Kermit) ended up letting him charge up the attack, due to Cell being angered that they cannot pull a good joke. In the end, when Kermit mocks Cell by claiming that Baby is "too much" for him to handle, the annoyed and insulted Bio-Android angrily fires a Full Power Death Beam directly to Baby's crotch area before he could fully charge up the attack, killing him. His corpse ended up falling into Shallot's new car, where it exploded.

Trivia

 * Both Baby and Cell are far more alike than they would admit. Both are artificial life-forms created for vengeance (Cell was created to kill Goku over the destruction of the Red Ribbon Army, while Baby was created to destroy the Saiyan race, who annihilated the Tuffles), both rely on other people to gain power (Baby brainwashes people or takes control of their bodies while Cell absorbed others to gain their strength), and both could not care at all about their masters (Baby killed his creator Dr. Myuu for forgetting he was in charge, and Cell ultimately went against Dr. Gero's ambition to kill Goku, and ultimately started doing his own thing).