Monster is a friendly monster, and best friend of Frederwick. They originally met when Frederwick was out pretending to be a vampire slayer, and Frederwick thought Monster was bad, so he beat him up, since Monster didn't want to hurt a baby. They eventually became friends though.
Monster is very strong, with extremely strong skin and can lift up a truck (although this is the heaviest thing he can lift. monster's skin is so strong that it can withstand bullets but if you shot repeatedly he will die.