2024Space Command Redemption— Greg Mazzey
2023Babylon 5: The Road Home— Lennier (voice)
2018What We Left Behind: Looking Back at Star Trek: Deep Space Nine— Self
2009The Face is Familiar— Narrator
2007Holly Hobbie and Friends: Surprise Party— Bud Morris (voice)
2006Robotların Saldırısı— Major Keith
2006Holly Hobbie and Friends: Christmas Wishes— Bud Morris / Judge #1 (voice)
2006Look, Up in the Sky! The Amazing Story of Superman— Self
2005Derailroaded— Self
2005Yüzük Tutkunları— Self
2004Comic Book: The Movie— Bill Mumy
2002Larry 'Wild Man' Fischer— Self
2000Behind the Dementia— himself
2000Boom! Hollywood's Greatest Disaster Movies— Self - Host
1999Attack of the 50 Foot Monster Mania— Narrator
1998Lost In Space Forever— Self (also archive footage)
1996Underground Adventure— Sam (voice)
1996The Monkey Prince— Sam (voice)
1995Three Wishes— Neighbor
1995The Fantasy Worlds of Irwin Allen— Self - Host
1994A Bewitched Christmas— Michael (as Billy Mumy)
1990Kaptan Amerika— Young General Fleming
1987Zabagabee— Art Barnes
1984Hard to Hold— The James Roberts Band - Keyboard
1983Twilight Zone: The Movie— Tim
1980Fish Heads
1977Sunshine Christmas— Weaver
1976Archie— Larry
1974The Rockford Files: Backlash of the Hunter— Nick Butler
1973Kelebek— Lariot
1973Sunshine— Weaver
1971Bless the Beasts & Children— Lawrence Teft
1969Rascal— Sterling North
1968Wild in the Streets— Boy (uncredited)
1965Dear Brigitte— Erasmus 'Ras' Leaf
1965Lost in Space - No Place to Hide— Will Robinson
1964For the Love of Willadean— Freddy Gray
1963A Ticklish Affair— Alex Martin
1963A Child Is Waiting— Child
1963Palm Springs Weekend— Boom Boom Yates
1962Sammy, the Way-Out Seal— Petey Loomis
1961Tammy Tell Me True— Neil Bateman
1961The Wizard of Baghdad— Aladdin
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