DOCTOR WHO IN DETAIL

Commander Gustave Lytton was first encountered by the Fifth Doctor helping the Daleks. Lytton was commanding a task force that was attempting to rescue Davros from a prison ship. He also travelled to Earth, disguised as a policeman, using the Daleks' time corridor to kill a number of Dalek human replicas that had escaped.

During the chaos of a battle between Dalek factions and humans Lytton, again disguised as a policeman, managed to escape into London. Over time he turned to organising robberies and using the proceeds to buy electronic equipment to create a transmitter.

Lytton's transmission was picked up by the Cryons, and the Sixth Doctor. The Cryons employed Lytton to retrieve a time vessel that the Cybermen had stolen. To do this Lytton pretended to be on the side of the Cybermen. When the Cybermen discovered this ruse they tortured Lytton and started to covert him into a Cyberman.

Before the conversion process was complete Lytton managed to sacrifice himself to kill the Cyberleader.