Theodore Thomson Flynn MBE FLS FZS FRS MRIA (11 October 1883 – 23 October 1968) was an Australian zoologist and marine biologist and a professor in both Tasmania and the United Kingdom. He was the father of the actor Errol Flynn.

Theodore Thomson Flynn was born in Coraki, New South Wales, Australia, the son of Jessie B. (née Thomson) and John Flynn.^[1] He became a biology lecturer at the University of Tasmania in 1909, becoming professor in 1911 and teaching there until 1930.^[2]

He married Lily Mary (Marelle) Young on 23 January 1909; they had one child together, the film actor Errol Flynn.^[3] Flynn and his family then moved to Northern Ireland where he served as the Chair of Zoology at Queen's University of Belfast from 1931 to 1948; he also became director of the marine station at Portaferry.^[3]

After the Belfast Blitz, Flynn was the chief casualty officer for the city.^[4] On 1 January 1945, Flynn was awarded an Order of the British Empire for his service.^[5]

Flynn named one new species of sub-tropical kelpfish he discovered – Gibbonsia erroli – after his son.^[6]

Flynn died in Liss, Hampshire, England.^[7]

Flynn Lake, Macquarie Island was named after Flynn.^[1]