Before becoming Mojo Jojo, the main villain in The Powerpuff Girls was called Jojo.
Jojo was Professor Utonium’s laboratory assistant monkey before the creation of the Powerpuff Girls. In the origin story, the accident involving Chemical X gives the girls their powers and also affects Jojo. The resulting transformation makes him highly intelligent and leaves him with the distinctive enlarged brain and speech pattern associated with Mojo Jojo.
The character later becomes one of the girls’ most persistent enemies. Mojo Jojo typically operates from his volcano-shaped lair and uses elaborate machines or plans in attempts to conquer Townsville. Despite his intelligence, his schemes regularly fail because of the girls’ teamwork and his own overcomplication.
The name “Mojo Jojo” is therefore not simply an unrelated villain name; it grows out of the character’s earlier identity as Jojo. Some summaries focus only on Mojo Jojo and omit his pre-transformation role, which is why the origin detail can be easy to miss. The answer is the short original name: Jojo.