Theodore Thomson Flynn (11 October 1883 - 23 October 1968) was an Australian marine biologist and a professor in both Tasmania and the United Kingdom.
Flynn was born in Coraki, New South Wales, Australia, the son of Jessie B. (née Thomson) and John Flynn. He became a biology lecturer at the University of Tasmania in 1909, becoming professor in 1911 and teaching there until 1930. He married his wife, Lily Mary (Marelle) Young on 23 January 1909. Flynn then moved to Northern Ireland where he served as the Chair of Zoology at Queen's University of Belfast from 1931-1948. After the Belfast Blitz Flynn was the Chief Casualty Officer for the city. He was the father of film actor Errol Flynn, and named one new species that he discovered – Gibbonsia erroli – after his son. Theodore Flynn died in Liss, Hampshire, England.