Yellow robot

From Tardis Wiki, the free Doctor Who reference

A Yellow Robot was sent to Earth to find the heir to the throne of their planet. Along with a Red Robot, they removed all the Humans from Earth while they searched. The heir, a half-Human called Gavin, was hidden by a Bio damper. When removed, the robots recognised him. They returned the Humans and took Gavin home. (SJA: The Empty Planet)