Mike the Mullet Thing
Mike is the main character of MTMT, which should be obvious to you, since the comic is named after him. He is an anthropomorphic square with a bad mullet, a goatee, and a moustache, and he gets into wacky adventures, often resulting in him getting hurt. What fun!
Pete is a hairless triangle with a moustache similar to Mike's, who is, for some reason, the only real friend Mike has. Oddly enough, Pete is not shown as being any more intelligent or less intelligent than Mike, although Mike tends to act less maturely than Pete.
Bill is a giant dollar bill, with a cousin named Cashy McCash. Bill wears a monocle. Smashing!