McIlhenny or McElhenny is an Irish surname commonly found in Donegal and Derry also found in the highlands of Scotland. They are a Sept of the Cenel Eogain race, son of Naill high king of Ireland. In Gaelic the name translates "servant of Saint Canice". Notable people with the surname include:
Don McIlhenny (born 1934), American football player
Edward Avery McIlhenny (1872–1949), American businessman and Arctic explorer
Edmund McIlhenny (1815–1890), American businessman and inventor of Tabasco sauce
Henry Plumer McIlhenny (1919–1986), American art collector
John Avery McIlhenny (1867–1942), American businessman, Rough Rider, and politician
Paul C. P. McIlhenny (1944–2013), American businessman and conservationist
Walter Stauffer McIlhenny (1910–1985) American businessman and World War II Marine
