Brian Patrick McGahen (3 March 1952 – 3 April 1990) was an Australian gay activist and social libertarian.
He was born at Camperdown in Sydney to hairdresser Patrick James McGahen and Monica Marie Anderson, née Pettit.
After attending De La Salle College Ashfield, he received a Bachelor of Social Studies from the University of Sydney in 1974.
As a student he opposed the Vietnam War, refusing to register for conscription; his advocacy of draft resistance led to his conviction for sedition.
Along with Craig Johnston and Bill Hunt, elected at the same time, he was the first openly gay member of the council.