Who was the oldest person to represent Australia at the Olympics?

Andrew Hoy (equestrian 1984-2004), Colin Beashel (sailing 1984-2004), and Colin Coates (speed skating 1964-1984) with 6 Olympic game appearances each.

Hoy won 4 medals (3 gold, 1 silver), Beashel won 1 medal (bronze), and Coates did not win a medal.