Go-Ray

The Go-Rays were the natives of the planet Go-Ray. They were humanoid except for a single wheel instead of legs, possessing metal bodies, large eyes and wide mouths. When the First Doctor, John and Gillian arrived on their planet, a group of Go-Ray police officers arrested them after one of their cardium reactors malfunctioned, believing them to be responsible for the accident. The travellers escaped and, making their way to a cave outside the Go-Ray city, acquired mercury to replace the cardium and repair the reactor. The Go-Rays tried to capture them at the cave, but the travellers escaped. The Go-Rays later found them in the reactor room and sealed them in, intending to recapture them, but let them go after the Doctor convinced them that they repaired the reactor and that he was a magician. (TVC: Enter: The Go-Ray)