Bus conductor (The Greatest Show in the Galaxy)

The Bus Conductor was an Android. It was temporarily disabled by the Seventh Doctor.

Later, the Chief Clown forced Bellboy to fix the Bus Conductor, and the Robot Clowns took it back to the bus. Kingpin and Ace went to collect something hidden aboard the bus and the Bus Conductor tried to kill them, but at that point Kingpin regained his memory and remembered how to destroy it.

Kingpin instructed Ace to press a button on the Bus Conductor's head. Ace did so, and got clear only seconds before the Bus Conductor blew up. (DW: The Greatest Show in the Galaxy)