Charles William "Bill" Mumy, Jr., is an American actor, musician, pitchman, instrumentalist, voice-over artist, and a figure in the science-fiction community. He is perhaps best known for his work as a child actor in film and television throughout the 1960s, then credited as Billy Mumy.
The red-headed Mumy came to prominence in the 1960s as a child actor, most notably as Will Robinson, the youngest of the three children of Professor John and Dr. Maureen Robinson and friend of the nefarious and pompous Dr. Zachary Smith, in the 1960s CBS sci-fi television series Lost in Space.
He later appeared as a 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 he also served as narrator of A&E Network's Emmy Award-winning series, Biography. He is notable for his musical career, as a solo artist and as half of the duo Barnes & Barnes.