Jack Strong

Jack Strong was the son of Harroll Strong and the twin brother of Dot Strong. He had a dead-white complexion and red hair.

Jack accompanied his father and sister on an Earth-Mars expedition to Corbo, during which he and Dot were the only ones not captured by the devil-birds. The First Doctor found them and, after rescuing the spaceship crew, took them to the TARDIS. (PROSE: The Devil-Birds of Corbo) Before being returned to Earth, they had at least one other adventure with him when they travelled to Rhoos. (PROSE: The Playthings of Fo)

Behind the scenes
Jack and his sister Dot are never depicted in the illustrations accompanying the short story, however they are depicted on the cover of the annual.