Frederick Marius

Professor Marius was a scientist who worked at the Bi-Al Foundation in the year 5000 as a specialist in extraterrestrial pathological endomorphisms. He was the creator and first master of K9 Mark I. (TV: The Invisible Enemy)

While off Earth Marius had a dog, Kelso. He could not to take Kelso to his new workplace at the laboratory of the Bi-Al Foundation. Marius left Kelso with Grace and constructed K9 to accompany and assist him in his work. (PROSE: One Man and His Dog)

He helped the Fourth Doctor defeat the Swarm, although he himself was briefly infected by it and so freed the Nucleus and made it grow in size. Afterwards, Marius gave K9 to the Doctor to take with him on his journeys. (TV: The Invisible Enemy)

Commenting some damages occured to K-9, Leela once said that professor Marius would haven't been very pleased about it. (TV: Image of the Fendahl)