Brendan John Mullin was born in Jerusalem on 30 October 1963. He was educated at Blackrock College and studied law at Trinity College in Dublin before going to Oxford and winning Blues in 1986 and 1987. A fine attacking centre for Blackrock College in senior rugby, he gained 55 caps for Ireland between 1984 and 1995 and scored 17 tries in international rugby. In 1989 he toured with the British Isles to Australia, scored a hat-trick of tries in the opening fixture against Western Australia, and finished with seven tries in seven appearances, including the first test. Brendan Mullin was also an international hurdler for Ireland. In addition to playing for the Barbarians against Australia in 1984, he was an unused replacement against New Zealand in 1989.