Mark Duncan or Marc Duncan may refer to:
Renaissance Mark Duncan (regent) (1570?–1640), Scottish regent of the University of Saumur Mark Duncan de Cérisantis (died 1648), son of the preceding, French and Swiss diplomat, and secretary to Henry II, Duke of Guise
Music Mark Duncan, English bass guitarist with The Dogs D'Amour in the 1980s Marc Duncan, American bass guitarist with Prayer for Cleansing in the 1990s Marc Duncan, English member of The Rockingbirds
Politics
Mark Duncan (politician), American politician from New Mexico
Television Mark Duncan, creator of several Bill & Ben Video Doctor Who episodes Mark Duncan, played Mark Tanner in Swift and Shift Couriers, Australian comedy series
Sport Mark Duncan (coach), American football player and coach, and basketball coach Mark Duncan, played basketball for Scotland at the 2006 Commonwealth Games Mark Duncan, interim Denver Pioneers men's basketball head coach in 1943 Mark Duncan, Kiama Knights rugby league player; 2004 Group 7 Player of the Year Mark Duncan, wide receiver on the 2009 Delaware Fightin' Blue Hens football team Marc Duncan, Dutch MMA fighter, lost a 2006 It's Showtime 70MAX MMA Championship title fight