[1] He attended Reed College in Portland, Oregon, where he began performing in improvisational theatre.
[1] Willson has appeared on shows including Laverne & Shirley as Eraserhead in episode "A Date with Eraserhead", and Full House as Stu in episode "Crimes and Michelle's Demeanor" in 1990, Curb Your Enthusiasm, Boston Public, Caroline in the City, The Newsroom and Star Trek: Voyager.
Willson also appeared on Garry Shandling's The Larry Sanders Show playing Larry's accountant, and the brother of Sid the cue card holder.
His film appearances include The Pack (1977), The Devonsville Terror (1983), My Best Friend Is a Vampire (1987), Moving (1988), 976-EVIL (1988), Problem Child 2 (1991), Circuitry Man (1990), Plughead Rewired: Circuitry Man II (1994) and the comedy film Office Space (1999) as one of "The Bobs".
Cheers producer Ken Levine has described Willson as "one of the greatest improv artists I have EVER seen.