Hennessey is an Irish surname, being the anglicised form of Ó hAonghusa. Families of this name were found in Kingdom of Uí Failghe and Kingdom of Desmond.
People with the surname Notable people with the surname include:
Brad Hennessey (born 1980), baseball player Charlotte Hennessey (1873–1928), Canadian actress; mother of Mary Pickford (Gladys Louise Smith), Lottie Pickford and Jack Pickford Dan Hennessey (1942–2024), American-Canadian voice actor Dorothy Hennessey (1913–2008), Roman Catholic religious sister and activist Erin Hennessey (born 1976), American politician from New Hampshire Gwen Hennessey (born 1932), Roman Catholic religious sister and activist John Hennessey, founder of Hennessey Performance Engineering Keith Hennessey, director of the U.S. National Economic Council Martha Hennessey (born 1954), American politician from New Hampshire Terry Hennessey (1942–2025), Welsh footballer Wayne Hennessey (born 1987), Welsh footballer
Fictional characters with the surname Alistair Hennessey, fictional rival to the eponymous character of The Life Aquatic with Steve Zissou
See also Hennessy (surname)