Geoffrey Windsor-Lewis (born 7 April 1936) is a Welsh former international rugby union player.
Born in Cambridge, England, Windsor-Lewis is the son of 1920s Wales fly-half Windsor Hopkin Lewis, who was a Cambridge University RUFC secretary and former blue.
Windsor-Lewis won two Cambridge blues and captained the team to victory in the 1958 Varsity match.
A Richmond player, Windsor-Lewis was capped twice by Wales in the 1960 Five Nations Championship, as a centre in matches against England at Twickenham and Scotland at home.
Windsor-Lewis toured with the Barbarians both as a player and assistant team manager. He was a long-time Barbarians honorary secretary and in 2010 was appointed vice-president.