Updated: October 05, 2025

From 1965 to 1968, Mumy portrayed Will Robinson in Lost in Space, the recipient of numerous warnings ( Including "Danger, Will Robinson" ) from the show's robot character, voiced by Dick Tufeld.

Mumy was later cast in Bless the Beasts and Children ( 1971 ) as Teft, a leader in a group of misfit teenage boys resolved to save a herd of bison from hunters. He also played a musician friend of Cliff DeYoung's character in the television film Sunshine ( 1973 ), later reprising the role in Sunshine Christmas ( 1977 ) and in the TV series Sunshine ( 1975 ). In 1974, Mumy played Nick Butler in the pilot episode of NBC's The Rockford Files and made an appearance in a later episode in season 1 as a sidewalk artist. In 1988, he played Ben Matlock's genius nephew, Dr. Irwin Bruckner, on Matlock.