Charles William Mumy Jr. (; born February 1, 1954) is an American actor, musician, pitchman, instrumentalist, voice actor, author and a figure in the science-fiction community/comic book fandom. He came to prominence in the 1960s as a child actor, when he was credited as Billy Mumy, an era which included appearances in The Twilight Zone and Alfred Hitchcock Presents television shows, as well as co-starring in Dear Brigitte, followed by an iconic three-season role as Will Robinson in the 1960s CBS sci-fi series Lost in Space.
He later appeared as lonely teenager Sterling North in the Disney film Rascal (1969). He played Teft in the film Bless the Beasts and Children (1971).
In the 1990s, he performed the role of Lennier in all five seasons of the syndicated sci-fi TV series Babylon 5, and narrated A&E Network’s Emmy Award-winning series Biography.
Mumy is also known for his musical career as a guitarist, singer, songwriter and composer: he is an Emmy nominee for original music in Adventures in Wonderland (1991). As a musician Mumy performs as a solo artist, an occasional guest performer, and as half of the duo Barnes & Barnes. From 1988 through the 90s he performed at the San Diego Comic-Con and other comics related events as part of the band Seduction of the Innocent (named after the book by Fredric Wertham) along with Miguel Ferrer, Steve Leialoha, Max Allan Collins and John “Chris” Christensen. The band released one CD, The Golden Age.