'''Trethowan''' is a Cornish surname, found both in Cornwall and amongst members of the Cornish diaspora. People with the name include:
* Anthony Trethowan (1945–2015), Australian politician * Arthur Trethowan (1863–1937), Australian politician * Ian Trethowan (1922–1990), British television executive * Illtyd Trethowan (1907–1993), British religious philosopher * John Trethowan (born 1936), Australian rules footballer * Pat Trethowan (born 1941), Australian rules footballer * Rebecca Trethowan (born 1985), New Zealand rugby union player * Perry Trethowan, a fictional detective in a series of books by Robert Barnard *Sir William Trethowan ( ) British professor of psychiatry, Birmingham University
==See also== * Trethowan's sign
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Category:Cornish-language surnames