Ian Cassan Messiter (2 April 1920 – 22 November 1999) was a BBC Radio producer and the creator of a number of panel games, including Just a Minute, and Many a Slip. Messiter also brought the successful Twenty Questions format to BBC Radio. He was also the Programme Associate on Family Fortunes. Messiter was born in Dudley, Worcestershire and educated at Sherborne School in Dorset. He acted as whistle blower on both One Minute Please and Just a Minute. He published his autobiography My Life and Other Games in 1990.
Messiter married Enid, née Senior. They had two children; a daughter Susan, who lives in Cambridgeshire and a son, Malcolm Messiter, who is a world-renowned oboist, and four grandchildren; James, Toby and Emily Beaumont and Helen Messiter.