You can't have Bloo without Mac, so here he is. As you can see Mac went through a big change. He started out more of a "Peanuts" "Dennis the Menace" type kid but there was something about this design that didn't feel right. He felt dated to me or something and I could never really "connect" to this kid. So I quickly changed the design of the head there he was.
Only afterwards did my family point out that he looks just like me at that age. I can totally see it now, but at the time it was totally subconcious.