William O'Neill
William O'Neill is the name of the following people:
- William O'Neill (badminton) , Irish badminton player
- William A. O'Neill ( William Atchison O'Neill ; 1930-2007), American politician
- William L. O'Neill ( William Lawrence O'Neill ; 1935-2016), American historian
- William P. O'Neill (1874–1955), American politician