One of the lesser known Doctor Who villains was a robot by the name of Voc. Reprogrammed by an evil scientist, Vocs became killers. The Robots of Death was voted as one of the best Doctor Who stories.
Doctor Who starring Tom Baker in The Robots of Death by Chris Boucher, first broadcast in 1977. The Doctor faces a horrific army of merciless machines… On a desolate planet rich in metal ores a huge sandminer crawls over the barren wastes scraping the surface for lacunal, one of the most valuable substances in the Universe. The skeleton crew are served by their robot staff; efficient, expendable and totally obedient. Until now. One by one the human crew are brutally and mysteriously eliminated and suspicion shifts from the crew members themselves to the Doctor and Leela, who have accidentally landed on the planet. But, as the true enemy is revealed, the Doctor, Leela and the remains of the terrified crew find themselves prey to a horde of killer robots answerable only to an evil scientist determined to see them seize absolute power.