MacSween and McSween are surnames of Gaelic origin. People with those surnames include:
Alexander McSween (c.1843-1878), Canadian-American participant in the Lincoln County War of 1878Donald McSween (born 1964), American ice hockey playerHarold B. McSween (1926–2002), U.S. Representative from Louisiana.Harry McSween (born 1945), American geologist and planetologistJohn MacSween (fl. 1310), Scottish noblemanJohn MacSween (haggis entrepreneur) (1939–2006), Scottish butcher and entrepreneurMacSween, a Scottish company founded by John MacSween, known for making haggisRoderick MacSween (born 1935), Scottish pathologistSusan McSween (1845–1931), American rancher