Updated: March 24, 2022

The Robot: The Robot is a Class M-3 Model B9, General Utility Non-Theorizing Environmental Control Robot, which had no given name. 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. The Robot was performed by Bob May in a prop costume built by Bob Stewart. The voice was dubbed by Dick Tufeld, who was also the series' narrator.

The Robot was designed by Robert Kinoshita, whose other cybernetic claim to fame is as the designer of Forbidden Planet's Robby the Robot. Robby appears in LIS #20 "War of the Robots", and the first episode of season three; "Condemned of Space".