William O'Reilly
William O'Reilly or Bill O'Reilly may refer to:
- Bill O'Reilly (cricketer), Australian cricketer
- Bill O'Reilly (political commentator), American commentator, author and television host
- William O'Reilly (MP), UK MP for the Irish constituency of Dundalk, 1832–1835
- William O'Reilly (educator), Irish educator
- William Edmund O'Reilly, British diplomat
- William F. B. O'Reilly, American political consultant