37 credits
- Space Command Redemption
2024 Greg Mazzey
- Babylon 5: The Road Home
2023 Lennier (voice)
- The Face is Familiar
2009 Narrator
- Holly Hobbie and Friends: Surprise Party
2007 Bud Morris (voice)
- A.I. Assault
2006 Major Keith
- Holly Hobbie and Friends: Christmas Wishes
2006 Bud Morris / Judge #1 (voice)
- Comic Book: The Movie
2004 Bill Mumy
- Behind the Dementia
2000 himself
- Attack of the 50 Foot Monster Mania
1999 Narrator
- Lost in Space Forever
1998 Writer
- Underground Adventure
1996 Sam (voice)
- The Monkey Prince
1996 Sam (voice)
- Three Wishes
1995 Neighbor
- A Bewitched Christmas
1994 Michael (as Billy Mumy)
- Double Trouble
1992 Bob
- Captain America
1990 Young General Fleming
- Zabagabee
1987 Writer
- Hard to Hold
1984 The James Roberts Band - Keyboard
- Twilight Zone: The Movie
1983 Tim
- Fish Heads
1980 Musician
- Sunshine Christmas
1977 Weaver
- Archie
1976 Larry
- The Rockford Files: Backlash of the Hunter
1974 Nick Butler
- Papillon
1973 Lariot
- Sunshine
1973 Weaver
- Bless the Beasts & Children
1971 Lawrence Teft
- Rascal
1969 Sterling North
- Wild in the Streets
1968 Boy (uncredited)
- Dear Brigitte
1965 Erasmus 'Ras' Leaf
- Lost in Space - No Place to Hide
1965 Will Robinson
- For the Love of Willadean
1964 Freddy Gray
- A Ticklish Affair
1963 Alex Martin
- A Child Is Waiting
1963 Child
- Palm Springs Weekend
1963 Boom Boom Yates
- Sammy, the Way-Out Seal
1962 Petey Loomis
- Tammy Tell Me True
1961 Neil Bateman
- The Wizard of Baghdad
1961 Aladdin
