Thornton Gainsborough Clarke (27 November 1891 – 19 July 1916) was an Australian rules footballer who played with Fitzroy in the Victorian Football League (VFL).
As a 19-year-old, Clarke appeared in four games in the 1911 VFL season, his only year at the club.He later enlisted with the Australian Army and joined the 60th Infantry Battalion.
Clarke was killed in action soon after arriving on the Western Front, during the Battle of Fromelles.