Red Robot

A red robot was sent to Earth to find the heir to the throne of its planet.

Along with a yellow robot, it removed all the humans, apart from Clyde Langer and Rani Chandra who were "grounded" by the Judoon, from Earth while they searched. The heir, a half-human called Gavin, was hidden by a bio damper. When removed, the robots recognised him. At his order, they returned the humans and took Gavin home.

_{Biography from the TARDIS Data Core article, licensed under CC-BY-SA}