Updated: March 07, 2025

Although a machine endowed with superhuman strength and futuristic weaponry, he often displayed human characteristics, such as laughter, sadness, and mockery, as well as singing and playing the guitar. With his major role often being to protect the youngest member of the crew, the Robot's catchphrases were "That does not compute" and "Danger, Will Robinson!", accompanied by flailing his arms.

The Robot was performed by Bob May in a prop costume built by Bob Stewart. The voice was primarily dubbed by Dick Tufeld, who was also the series' narrator, and Jorge Arvizu for the Spanish dubbing. The Robot was designed by Robert Kinoshita, who also designed Forbidden Planet's Robby the Robot. Both robots appear together in Lost in Space episode #20, "War of the Robots", and in episode #60, "Condemned of Space". The Robot did not appear in the unaired pilot episode, but was added to the series once it had been greenlit.