Mojo is a chimpanzie whose brain grows bigger after he rudely pushed Professor Utonium by dropping Chemical X and give birth to the Powerpuff Girls. Mojo plotted to take over Townsville - only to get beaten up by The Girls and thrown away in jail. He even created The Rowdyruff Boys (Male Counterparts to The Girls).
Jojo turns out to be one of some of the most evilist of the show's villains and is best known for saying CURSES!
He even played a major role in The Powerpuff Girls Movie (Prequel to the television show). In fact, in that movie, he is the main antagonist.
Mojo Jojo will appear in 2017 crossover cartoon tv series Castaras, as a villian. along with Bubbles as his rival.