Irwin has a few recognizable TV roles to his name. His clowning and mime experience came in handy playing the silent Mr. Noodle on the "Elmo's World" segments of Sesame Street. In a Playing Against Type turn he played Raymond Langston's arch-nemesis Nate Haskell on CSI. On Legion he played Cary Loudermilk, half of a pair of symbiotic twin mutants, with his sister Kerry portrayed by Amber Midthunder, a Native American actress 47 years Irwin's junior.
Not to be confused with Bill Erwin.
Roles
Film
- 1980 Popeye as Ham Gravy
- 1988 Eight Men Out as Eddie Collins
- 1990 My Blue Heaven as Kirby
- 1991 Hot Shots! as Buzz Harley
- 2000 How the Grinch Stole Christmas! as Lou Lou Who
- 2004 The Manchurian Candidate as Scoutmaster
- 2006 Lady in the Water as Mr. Leeds
- 2007 Across the Universe (2007) as Uncle Teddy
- 2008 Rachel Getting Married as Paul
- 2014 Interstellar as voice of TARS
Television
- 1987 The Cosby Show as Eddie Bartholomew
- 1991-92 Northern Exposure as Enrico Bellati
- 1992-2009 Sesame Street as Mr. Noodle/Air Mime/Professor Television
- 1996 The Adventures of Pete & Pete as The Broker
- 1998 3rd Rock from the Sun as Pickles
- 2006 Law & Order: Criminal Intent as Nate Royce
- 2008 Law & Order as Ellison Conway
- 2008-11 CSI as Nate Haskell
- 2011 The Good Wife as Fred Medkiff
- 2013-20 Law & Order: Special Victims Unit as Dr. Peter Lindstrom
- 2014 Elementary as Richard Balsille
- 2014 Blue Bloods as Cardinal Brennan
- 2015-16 Sleepy Hollow as Atticus Nevins
- 2017-19 Legion as Cary Loudermilk
- 2020 Star Trek: Discovery as Su'kal
