Charles O'Neill may refer to:
- Charles O'Neill (musician) (1882–1964), Canadian bandmaster, composer, organist, cornetist, and music educator
- Charles O'Neill (Pennsylvania politician) (1821–1893), U.S. Representative from Pennsylvania
- Charles Gordon O'Neill (1828–1900), Australasian philanthropist and politician
- Charles H. O'Neill (1800–1897), U.S. politician
- Charles O'Neill, 1st Earl O'Neill (1779–1841), Irish politician, peer and landowner
- Charles O'Neill (Irish politician), Member of Parliament for South Armagh, 1909–1918