Bill Mumy Charles William "Bill" Mumy, Jr. (/'mu?mi/; born February 1, 1954), is an American actor, musician, pitchman, instrumentalist, voice actor, and a figure in the science-fiction community. He came to prominence in the 1960s as a child actor, when he was credited as Billy Mumy. His most notable role was in the 1960s CBS sci-fi television series Lost in Space, where he played Will Robinson, the youngest of three children in the Robinson family. He later appeared as lonely teenager Sterling North in the 1969 Disney film Rascal with Steve Forrest. He was cast as Teft in the 1971 film Bless the Beasts and Children. In the 1990s, he had the role of Lennier in the syndicated sci-fi TV series Babylon 5, and also served as narrator of A&E Network's Emmy Award-winning series Biography. He is notable for his musical career, with an Emmy nomination for original music in Adventures in Wonderland (1991), as a solo artist, and as half of the duo Barnes & Barnes.