Harold James Frith AO (16 April 1921 – 28 June 1982) was an Australian administrator and ornithologist. He was born at Kyogle, New South Wales and studied Agricultural Science at Sydney University. Harry Frith (as he was usually known) first joined the CSIRO Division of Plant Industry but later transferred to the Division of Wildlife and carried out extensive research on malleefowl, waterfowl, especially magpie geese, and pigeons. He eventually became Chief of the Division and was instrumental in proposals that led to the establishment of Kakadu National Park.
Harry Frith was a member of the Royal Australasian Ornithologists Union (RAOU), and prominent among those pressing for reform of the organisation in the late 1960s. He was Secretary-General of the 16th International Ornithological Congress held in Canberra in 1974. Frith was elected a Fellow of the RAOU in 1974. He was an Officer of the Order of Australia.