Costigan (Irish: Mac Oistigin) is an Irish surname with higher concentrations in Counties Laois, Tipperary and Kilkenny. Costigan is thought to be a branch of the Mac Giolla Phádraig dynasty of Osraige. Notable people with the surname include:
Christopher Costigan, explorer of the Jordan River and Dead Sea in 1835Daniel Costigan, former Commissioner of An Garda SíochánaEdward P. Costigan (1874–1939), US senator from ColoradoFrancis Costigan, early Indiana architectFrank Costigan, (1931–2009) Australian QC and commissioner in the Royal Commission on the activities of the Federated Ship Painters and Dockers Union (known as the Costigan Commission)Giovanni Costigan (1905–1985), historianGeorge Costigan (born 1947), a British television actorHoward Costigan (1904–1985), American political functionaryJames Costigan, screenwriterJason Costigan, Australian Liberal National politician and former rugby commentatorJohn Edward Costigan, American artistJohn Costigan (hurler)Keith Costigan, former soccer player, and television sports analystMichael Costigan (entrepreneur)Michael Costigan (film producer)Michael Costigan (youth speaker)Neville Costigan, Australian rugby league footballerPeter Costigan, (1935–2002), Australian journalist, former Lord Mayor of MelbourneSandra Costigan, former field hockey playerFictional characters:
Billy Costigan, a character in the Martin Scorsese film, The Departed, played by Leonardo DiCaprioCaptain Costigan, a character in the novel Pendennis, by William Makepeace Thackeray.Sailor Steve Costigan, a character created by Robert E. HowardConway Costigan, a character in E.E. Smith's TriplanetaryJerry, Grace and Russell Costigan, characters in Robert B. Parker's novel "A Catskill Eagle"