Ardagh is a toponymic surname, from the Irish place name Ardagh (from Irish Gaelic ard áth, "high field"). Notable people with the surname include:
Politics Catherine Ardagh (born 1982), Irish politician, Senator for the Industrial and Commercial Panel Dick Ardagh (1871–1931), Australian politician Seán Ardagh (1947–2016), Irish politician, TD for Dublin South-Central William Davis Ardagh (1828–1893), Canadian politician
Other John Ardagh (1928–2008), British writer John Charles Ardagh (1840–1907), British Army officer Osmond Ardagh (1900–1954), English cricketer Philip Ardagh (born 1961), British writer
See also Henry de Ardagh, Dean of Armagh, Church of Ireland, in the 13th century Mél of Ardagh (died 488), Irish saint, nephew of St. Patrick