 Space Command Redemption2024 · Greg Mazzey | Greg Mazzey |
 Babylon 5: The Road Home2023 · Lennier (voice) | Lennier (voice) |
 What We Left Behind: Looking Back at Star Trek: Deep Space Nine2018 · Self | Self |
 The Face is Familiar2009 · Narrator | Narrator |
| HHolly Hobbie and Friends: Surprise Party2007 · Bud Morris (voice) | Bud Morris (voice) |
 Holly Hobbie and Friends: Christmas Wishes2006 · Bud Morris / Judge #1 (voice) | Bud Morris / Judge #1 (voice) |
 A.I. Assault2006 · Major Keith | Major Keith |
 Look, Up in the Sky! The Amazing Story of Superman2006 · Self | Self |
 Derailroaded2005 · Self | Self |
 Ringers: Lord of the Fans2005 · Self | Self |
 Comic Book: The Movie2004 · Bill Mumy | Bill Mumy |
| LLarry 'Wild Man' Fischer2002 · Self | Self |
 Behind the Dementia2000 · himself | himself |
| BBoom! Hollywood's Greatest Disaster Movies2000 · Self - Host | Self - Host |
 Attack of the 50 Foot Monster Mania1999 · Narrator | Narrator |
 Lost In Space Forever1998 · Self (also archive footage), Writer | Self (also archive footage), Writer |
 The Monkey Prince1996 · Sam (voice) | Sam (voice) |
 Underground Adventure1996 · Sam (voice) | Sam (voice) |
 Three Wishes1995 · Neighbor | Neighbor |
 The Fantasy Worlds of Irwin Allen1995 · Self - Host | Self - Host |
 A Bewitched Christmas1994 · Michael (as Billy Mumy) | Michael (as Billy Mumy) |
 Double Trouble1992 · Bob | Bob |
 Captain America1990 · Young General Fleming | Young General Fleming |
 Zabagabee1987 · Art Barnes, Writer | Art Barnes, Writer |
 Hard to Hold1984 · The James Roberts Band - Keyboard | The James Roberts Band - Keyboard |
 Twilight Zone: The Movie1983 · Tim | Tim |
 Fish Heads1980 · Actor | Actor |
 Sunshine Christmas1977 · Weaver | Weaver |
| AArchie1976 · Larry | Larry |
 The Rockford Files: Backlash of the Hunter1974 · Nick Butler | Nick Butler |
 Papillon1973 · Lariot | Lariot |
 Sunshine1973 · Weaver | Weaver |
 Bless the Beasts & Children1971 · Lawrence Teft | Lawrence Teft |
 Rascal1969 · Sterling North | Sterling North |
 Wild in the Streets1968 · Boy (uncredited) | Boy (uncredited) |
 Dear Brigitte1965 · Erasmus 'Ras' Leaf | Erasmus 'Ras' Leaf |
 Lost in Space - No Place to Hide1965 · Will Robinson | Will Robinson |
 For the Love of Willadean1964 · Freddy Gray | Freddy Gray |
 Palm Springs Weekend1963 · Boom Boom Yates | Boom Boom Yates |
 A Ticklish Affair1963 · Alex Martin | Alex Martin |
 A Child Is Waiting1963 · Child | Child |
 Sammy, the Way-Out Seal1962 · Petey Loomis | Petey Loomis |
 Tammy Tell Me True1961 · Neil Bateman | Neil Bateman |
 The Wizard of Baghdad1961 · Aladdin | Aladdin |
