Theodore Leighton Pennell (1867 – 23 December 1912), was an English Protestant missionary and doctor who lived among the tribes of Afghanistan. He founded Pennell High School and a missionary hospital in Bannu in the North-West Frontier of British India, now Pakistan. For his work he received the Kaisar-i-Hind Medal for public service in India. He published a work on his life under the title Among the wild tribes of the Afghan frontier in 1908.Pennell House at Eastbourne College was named after him.