Thomas Campion Trewin (9 October 1914 – 14 July 1992) was an Australian politician.
He was born in Benalla to farmer Percy Charles Trewin and schoolteacher Ellen Alice Bradbury.
Educated at Goorambat and Benalla, he became a farmer at Devenish.
On 23 March 1940 he married Eliza May Martin; they had four children.
Active in both the local community and the local Country Party, he was elected to the Victorian Legislative Assembly in 1961 as the member for Benalla.