Frederick Marius

Professor Marius was a scientist who worked at the Bi-Al Foundation in the 50th century as a specialist in extraterrestrial pathological endomorphisms. He constructed K-9 to accompany and assist him in his work. He helped the Doctor defeat the Swarm, although he himself was briefly infected by it. Afterwards, Marius gave K-9 to the Doctor to take with him on his journeys. (DW: The Invisible Enemy)