Henry O'Neill (1891–1961) was an American film actor.
Henry O'Neill may also refer to:
- Henry O'Neill (d. 1347), king of Tyrone
- Henry O'Neill (illustrator) (1798–1880), Irish artist and antiquarian
- Henry O'Neill (darts player), Northern Irish darts player
- Henry O'Neill, 2nd Baron Dungannon, held title Baron Dungannon
- Sir Henry O'Neill, 3rd Baronet (c. 1674–1759) of the O'Neill baronets
- Sir Henry O'Neill, 1st Baronet (1625-c. 1680) of the O'Neill baronets
- Henry E. O'Neill (1848–1925), British explorer of Central Africa
- Henry MacShane O'Neill (died 1622), leader of the MacShane (not to be confused with MacShane's of Loughinsholin)
- Henry O'Neill (bishop) (1843–1915), Irish bishop of Dromore