Constantine is the secondary antagonist of Robotboy. He is a fat hunchbacked Anti-Villain henchman of Dr. Kamikazi who also is a master of sumo wrestling (though it is unknown if he has ever been a yokozuna, or "grand champion"). He is a sensitive and none too threatening sidekick to Dr. Kamikazi who mainly acts as his muscle power as well as his assistant. Constantine is also a refined chef, being able to create dishes ranging from Sashimi to tapas. It was seen in one episode that Constantine used to be an orphan before working for Kamikazi.
Despite looking like a Japanese version of a henchman, Constantine is actually Spanish, suggesting that his outfit is simply a uniform assigned to him by Dr. Kamikazi.