Major Jacques Theodore Paul Marie Vaillant de Guélis (6 April 1907 - 7 August 1945) was a Wales-born French Special Operations Executive (SOE) agent during the Second World War.
De Guélis was initially in the British Expeditionary Force in France in 1940 and later joined SOE and parachuted into France to organise resistance networks.
He was badly injured in a motor accident in August 1945 and later died of his injuries in hospital.