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.

He was taller than Chertzog and had grey hair. (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.