Harroll Strong was the father of Jack and Dot Strong. He led an Earth-Mars expedition to Corbo in search of mineral deposits. He and his crew were captured by Ulla's devil-birds and he was nearly executed, but the First Doctor freed them and they escaped 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)
Harroll Strong had unruly red hair and was taller than Chertzog, Hill, and Shelly. (PROSE: The Devil-Birds of Corbo)