Dr. Julius Hibbert

He is the basically kind-hearted family doctor of the Simpson family. He is African-American, one of the few amongst the show's regular characters. He is noticably less dysfunctional than just about everyone else on the show, though he does have a bizarre tendency to laugh at inappropriate moments.

He is often seen in flashbacks (eg Lisa's birth, Bart's accidents as a toddler), and each time has a different hairstyle (afro, Bob Marley-ish, Mr T.[?], etc).

It's implied that he and Bleeding Gums Murphy are long-lost brothers.

See List of characters from The Simpsons.