Fahy is a surname derived from the Irish surname Ó Fathaigh. Alternative spellings include Fahie, Fahey and Fay.
People named Fahy include: Anthony Dominic Fahy, (1805–1871), Irish Dominican priest and missionary Charles Fahy (1892–1979), Solicitor General of the United States Edward Francis Fahy (1922–2005), Irish physicist and administrator Francis Arthur Fahy (1854–1935), Irish nationalist, songwriter and poet Francis Patrick Fahy (1880–1953), Irish teacher, barrister and politician Greg Fahy, cryobiologist and biogerontologist Jack Fahy, U.S. government official Jim Fahy (1946–2022), Irish broadcaster, journalist and documentary-maker John Fahy, Scottish football player Meghann Fahy (born 1990), American actress and singer Michael Fahy, Irish farmer and politician Ollie Fahy (born 1975), Irish hurler Pádraic Fahy (born 1948), Irish sportsperson Patricia Fahy, American politician Sir Peter Fahy (born 1959), British police officer Shea Fahy (born 1962), Gaelic football player