Ronald Alfred St Clair Brewer (8 April 1921 – 16 June 2003) was an Australian politician.
Born in Watsons Bay, Sydney to farmer Alfred George Brewer and Doris Griffin, he was educated at Gunning, Goulburn and Naremburn, leaving school at the age of 14.
He was discharged as medically unfit in 1942, and joined the Second Australian Imperial Force, being stationed in New Guinea as a warrant officer.
As an ex-serviceman he was settled with the Green Hills property near Marulan in 1948, and he became captain of the local Bush Fire Brigade.
Narrowly defeated by sitting Labor MP Jim Snow, Brewer contested the by-election for his old state seat and was re-elected.