White Robot

From Tardis Wiki, the free Doctor Who reference

The White Robots were a force controlled by the Master of the Land of Fiction or the Master Brain. They patrolled the White Void outside the Land but also serviced the Master in his castle within the Land. They possessed beams inside their chests that could disorient or destroy targets. While they may not have been characters, they were still connected to the Land (or the Master Brain) and if it was destroyed so were they. (TV: The Mind Robber)

The White Robots were later made to serve the Cybermen and were more advanced than previously seen. (AUDIO: Legend of the Cybermen)

White Robots on a slave ship. (COMIC: Bazaar Adventures)

Jason, a later Master, used the White Robots to clean up the messes he made bringing real people into the Land to turn them fictional. He later had them accost Ace in the Void and used two to bring the Seventh Doctor to him. (PROSE: Conundrum)

White Robots also existed within the real universe, guarding a ship during a slave trade. With the help of the Second Doctor, Jamie McCrimmon, and Zoe Heriot, the slaves revolted, destroying most of the white robots. (COMIC: Bazaar Adventures)

Behind the scenes