Hill (The Playthings of Fo)

Following the First Doctor's emergency evacuation of the Council of Earth and Mars mission to Corbo, Hill was a companion of the First Doctor. He travelled alongside Dr Harroll Strong, and Strong's children, Jack and Dot, as well as Shelly and Chertzog. (PROSE: The Playthings of Fo)

Behind the scenes
Though a member of the Earth-Mars mission to Corbo, is not actually introduced or mentioned until The Playthings of Fo.