This actor played a shell-shocked Starfleet officer in the critically acclaimed DS9 episode "The Siege of AR-558". As a musician, he was one half of the comic rock duo Barnes & Barnes that recorded the cult classic "Fish Heads". In 1961, he played the all-powerful monster Anthony Fremont in The Twilight Zone episode "It's a Good Life". Identify this actor who is best known for playing Lennier on Babylon 5 and for playing the oft in danger Will Robinson on the classic series Lost in Space
Bill Mumy