Joined Chicago's acclaimed Second City comedy troupe after graduating from college and remained a member until 1987.
Met his wife, writer-actor Deb Lacusta, in a Second City improv class; they went on to collaborate on many projects, including their own Chicago radio show.
Made his big-screen acting debut in the 1986 comedy Nothing in Common, which was followed by a bit part in the 1989 romantic-comedy classic Say Anything...
Has said the original vocal inspiration for Homer Simpson—back when The Simpsons was an animated short on The Tracey Ullman Show—was actor Walter Matthau; Homer's signature "D'oh!" was adapted from Scottish actor James Finlayson, who appeared in Laurel and Hardy movies.
In the late '90s, wrote the comedy play A Purple Dawn, which went on to be produced on some college campuses.
Released Two Lips, an album of Beatles-style pop-rock, in 2000; it was followed in 2002 by I Am Not Homer, a comedy cowritten by and featuring his wife, Deb.
Lends his voice to a multitude of other characters on The Simpsons, including Grandpa Simpson; Krusty the Clown; Groundskeeper Willie; Barney Gumble; Mayor Quimby; and Sideshow Mel.