Evil genius and criminal mastermind Dr. Katonian appears from time to time to boast about his latest dastardly scheme. His relationship with Kato is somewhat uncertain. Some believe they are one in the same, split personalities, Dr. Katonian existing as the megalomaniacal alter-ego to Kato's mild mannered self. Kato dismisses the claim, stating that he does a little IT work for Dr. Katonian and from time to time reposts the journal entries the Super Villain keeps.

Dr. Katonian resides in a secret hideout inside Mt. Kato (an ancient volcano) located on Kato Island. He is a highly motivated and moderately successful evil genius. Siphoning funs through his "legitimate" cover operation, Kato Korp. (and its subsidiaries including Katonian Industries, Kato Labs, The Katonian Institute For the Advancement of Evil, and the Happy Kitty Day Care chain) he vows to "take over the world and enslave you all". He likes moonlit walks along the crater of his volcanic hideout and enjoys ordering about minions and henchmen alike. He dislikes do-gooders and shellfish.

His other interests include: taking over the world, scheming, being evil, scheming some more, laughing maniacally, building/maintaining Death Rays, mayhem (general and specific), formulating devious plans, demanding ransoms of world leaders, being menacing, bedlam, mischief making, evildoing, plotting, stroking his evil goatee pensively, ordering around henchmen, and tending to butterfly gardens.