Marshal of Solos

The Marshal of Solos was the human military representative of the Earth Empire to Solos in the 30th century.

The Marshal enjoyed hunting and killing Solonian mutants. He strongly opposed the Empire's plan to grant Solos its independence, as it would mean an end to his career. He had Varan's son, Vorn, assassinate the administrator sent to grant it, accused Ky, and killed Vorn.

He then attempted to carry out his plan to permanently change the atmosphere of Solos to make it habitable for humans. He was defeated by the Third Doctor, and killed by Ky after he had metamorphosed into an advanced Solonian. (TV: The Mutants)

Behind the scenes
The Marshal is given some backstory in the novelisation: he is said to have joined Skybase One as a security guard, and worked his way up the ranks.