Colin James Oliver Harrison (18 August 1926 - 17 November 2003) was an English ornithologist. Harrison was born in London. He got a scholarship to grammar school, and then worked as a librarian and a teacher. He had been interested in birds since childhood, and joined an expedition to study autumn migration in Norway. He became a professional ornithologist at the age of 34 and became responsible for the care of the national collection of birds' nests and eggs in the Bird Room at the Natural History Museum at Tring, Hertfordshire. In 1966 he led the fourth of the series of Harold Hall Australian ornithological collecting expeditions.