File:Professor XXXL.jpg
Only minutes to go before my ingenius device is complete. Ant then I, Professor Triple X Large, will do something that change the world for kids everywhere. Bwahahaha!
~ Professor XXXL

Professor XXXL (pronounced "Triple Extra Large") is a villain from Codename: Kids Next Door. He is an insane, round-shaped scientist whose main goal is to create the perfect snowcone and is known for frequently mutating himself, having different animal parts in each of his appearances (such as a lobster claw, turtle shell and octopus tentacles). He is also bent on destroying the PTA (Parent-Teacher Organization) for some strange reason. He is a true villain.

He was voiced by Frank Welker.

While the Professor's actual goals are harmless, if not "good" by the show's standards (centered on the interests of children), his bizarre methods of reaching them, psychopathic tendencies and overall sinister demeanor make him much more dangerous than helpful and create the illusion that he is actually evil and out to harm children like the show's other villains, which is what causes him to be at odds with the KND; in both episodes where he is the main antagonist (Operation: A.R.C.T.I.C. and Operation: C.O.L.L.E.G.E.), the only reason the kids are fighting him is because they mistakenly believe he is behind some evil plot and attack him, causing the Professor to retaliate and ruining his snowcone experiments in the process, angering him further.

Professor XXXL is in fact a leftover character from Mr. Warburton's previous cancelled show attempt, "Kenny and the Chimp", from which the Kids Next Door originated as an idea and the pilot of which, which features the Professor, is included in the first episode of the show's run alongside the KND pilot. This may be the reason for the character's rather out-of-place role in the show.