Artificial beings created by the City of the Exxilons. They formed part of its defences. When the Doctor and Bellal penetrated to the City's control centre, and the Time Lord began to tamper with its electronic brain, the City created these creatures as antibodies to protect it from damage. They attacked the Doctor and Bellal, but were distracted by the arrival of a pair of Daleks. They were immune to bullets. The creatures would have been destroyed along with the City, once its energy-capturing beacon had been blown up.
Appearances: Death to the Daleks (1974).
- The pair were played by Terry Walsh and Steve Ismay, but went uncredited on screen. They did get a billing in the Radio Times for Part Four as "Zombies".