Sir John Chandos, Viscount of Saint-Sauveur in the Cotentin, Constable of Aquitaine, Seneschal of Poitou, KG (c. 1320 – 31 December 1369) is a medieval English knight who hails from Radbourne Hall, Derbyshire

Chandos is a close friend of Edward the Black Prince and a founding member and nineteenth Knight of the Order of the Garter in 1348.

Chandos is a gentleman by birth, but unlike most commanders of the day he holds no inherited title of nobility.

Described by the medieval historian Froissart as "wise and full of devices", as a military strategist Chandos is believed to have been the mastermind behind three of the most important English victories of the Hundred Years War: the Battle of Crécy, the Battle of Poitiers and the Battle of Auray.

His death in a minor skirmish was regretted by both sides.