The Man-Beast is a Werewolf that was originally meant to join Team Monster, but was rejected. The reason was his cursed, human self was considered too dangerous for the base due to his nerdy nature. His only appearance has been in Curse of the Man-Beast. Man-Beast is voiced by Will Friedle.
The Man-Beast was meant to be one of the first of the new recruits to Team Monster. Unfortunately General Monger quickly discovered that only on one night every month, the full moon, the Man-Beast was a exceptional combatant and competent member of the team. The rest of the month he was a overwhelmingly nerdy menace with a constant desire to press every button on the base.
Team Monster heard about this and for General Monger's birthday party they decided to give recruiting the were-wolf another shot. Susan Murphy instantly fell in love with the refined and sophisticated gentleman that was the Man-Beast during the full moon and in spite of his warning about his "terrible curse" the monsters found out the hard way when they got him back to the base.
Having since turned back to human the Man portion of the man beast resumed his rampage of klutziness and button pushing as Monger angrily explained why he left the were-wolf in the woods. Not one to give up on such a promising recruit Dr. Cockroach attempted to mad science a solution to their problem by rigging up a moon stone that could indefinitely keep him in his better half.
This attempt again backfired as the stone caused the Man-Beast transformation to spiral out of control and become feral, rampaging out of the base into The Diner where Monger was holding his birthday party. Left without any choice Susan was made to destroy the Moon Stone and shared a brief tender moment with the Man-Beast before the human half ruined the moment and rode off into the sun rise on a moped.
The Beast half of the Man-Beast is often a sophisticated, refined and charismatic gentleman with a love of romance novels and a preference for peace over violence.
Ironically the Man half of Man-Beast is considered the curse: a overwhelmingly nerdy man with a talent for stating the obvious, rather rudely, and an annoying penchant for pressing every button in sight.
One thing that both sides have in common is a rampantly affection for Susan Murphy, whereas the Beast approaches the romance in a proper manner the Man is a klutz, he is quick to point out her flaws and his accident prone manner ruins any hint of romance between the too.