William Clifford may refer to:

• William Clifford (priest) (died 1670), English Roman Catholic theologian
• William Clifford (cricketer) (1811–1841), English cricketer
• William H. Clifford (1862–1929), Ohio politician
• W. H. Clifford (William H. Clifford), writer, director, and film company head
• William Clifford (actor) (1877–1941), American actor of the silent era
• William Clifford (bishop) (1823–1893), English prelate of the Roman Catholic Church
• William Kingdon Clifford (1845–1879), mathematician and philosopher
• William Clifford Heilman (1877–1946), American composer
• Billy Clifford (soccer), American professional soccer player
• Billy Clifford (footballer) (born 1992), English professional footballer