William O'Reilly or Bill O'Reilly may refer to:
Bill O'Reilly (cricketer) (1905–1992), Australian cricketer Bill O'Reilly (political commentator) (born 1949), American commentator, author and television host William O'Reilly (MP) (1792–1844), UK MP for the Irish constituency of Dundalk, 1832–1835 William O'Reilly (educator) (1864–1937), Irish educator William Edmund O'Reilly (1873–1934), British diplomat William F. B. O'Reilly (born 1963), American political consultant
See also William Riley (disambiguation)