Proton (DBX)

Proton is a clone of Cell, created by King Cold to help him kill Freiza, who had rebelled against him. Proton eventually rebelled against his creator and absorbed him, ganing the ability to unlock higher forms that was native to Cold's species. With this power, he joined the X-Fighters and eventually grew to a level at which he was a match for a Super Saiyan God Super Saiyan, or even a Super Saiyan 5. He tried, and failed, to defeat Unleashed Beerus, along with the rest of the X fighters, including SSJGSSJ Goku, SSJSSJ Vegeta, SSJ2 Mystic Gohan, SSJ5 Tomata, Golden Freiza, and Android 17.5, and was killed along with Gohan and most of the rest of Earth's population. He was wished back to life a few years later, just in time to help defeat Golden King Cold and Golden Cooler, as well as Majin Bio Broly (Yep, they went there)