They should be in Pictures...
Here are the movies that the improv-ers on Whose Line Is It, Anyway? have been in (if an improv-er is not listed, it means they haven't been in movies; only on TV)
Ryan Stiles

Courting Courtney (1997)...Chad Gross
Hot Shots! Part Deux (1993)...Rabinowitz
Hot Shots! (1991)... 'Mailman' Farnham
Rainbow War (1985)
Colin Mochrie

Summer Storm (2003)....George Parker
The Tuxedo (2002) ....Gallery Owner
Expecting (2002) .... Gary
Do It for Uncle Manny (2002) .... Maitre 'D
Jane White Is Sick & Twisted (2002) .... Barney
Truth in Advertising (2001) .... John Stevenson
Totally Blonde (2001) .... Vulcan/Agent/Comic
The Midnight Hour (2000) (uncredited) .... Fred Dennis
Lucky Numbers (2000) .... Jack
Road to Nowhere (1999) .... Tom Berman
The Real Blonde (1997) .... Renny
January Man (1989) .... Pat
Rainbow War (1985)
Spacehunter: Adventures in the Forbidden Zone (1983) (uncredited) .... Guard
Brad Sherwood

Dill Scallion (1999) .... Brad Statlin
The Night Caller (1998) .... Andy Saden
That Darn Cat (1997) .... Team Agent #2
Greg Proops

Brother Bear (2003) (voice) .... Male Lover Bear
Kaena: La
prophétie (2003) (voice)
... aka Kaena: The Prophecy (2003) (USA)
Star Wars: The Phantom Menace (1999) (voice) .... Beed
The Nightmare Before Christmas (1993) (voice) (as Gregory Proops) .... Harlequin Demon, Devil, Sax Player
Pandemonium (1988) (uncredited) .... Voice-Over
West Is West (1987)
Chip Esten

Save It for Later (2003) .... Don
Ten Minutes Older: The Trumpet (2002) .... Bill (segment "Twelve Miles to Trona")
Thirteen Days (2000) .... Maj. Rudolph Anderson
The Postman (1997) ....
Michael, Abby's Husband
Drew Carey

Robots (2005)....
Rusties
Coneheads (1993) .... Taxi
Passenger