Hecorba

Hecorba - otherwise known as Hector Sharpe - was a fugitive and ally of the Cybermen.

History
Hecorba was wanted in five star systems for mass murder. During his days as a fugitive, Hecorba became allied with the Cybermen. They partially Cyber-converted Hecorba.

During the attempted invasion of Earth, Hecorba took the alias of "Hector Sharpe" and took a job as a doctor. This was a façade to gain victims for the Cybermen to convert.

Eventually, the Cyberman invasion was stopped by the Sixth Doctor and Peri and Hecorba was seemingly killed - his body destroyed (Human Intelligence)

However, Hecorba managed to survive in a robotic body. He started killing people to try and make a new body for himself. Hecorba also created an army of androids using the minds of his captives.

This was investigated by the Sixth Doctor and Mel - with the Doctor initially thinking that Hecorba had died after the end of the Cyberman invasion. Hecorba, however, had the Doctor brought to him. The Doctor was able to defeat Hecorba and his body was destroyed - killing him (Asimov's Unlawful)