Synopsis by Hal Erickson
The Robinsons' robot doesn't like the looks of the old, dilapidated robot that Will (Bill Mumy) has found and has decided to fix up. It seems that Will's robot is actually a "robotoid", capable of making its own decisions without human intervention. Sure enough, the robotoid turns out to have an evil streak, and is bent upon capturing the Robinsons and killing off their robot. The "villain" in this episode is played by the immortal Robby the Robot of Forbidden Planet fame, who like the Lost in Space robot was created by Bob Kinoshita.