William Warren is the name of:
- Sir William Warren (died 1602), Irish landowner, statesman and soldier
- William Warren (actor, born 1767) (1767–1832), American actor
- William Warren (actor, born 1812) (1812–1888), American actor
- William Warren (entomologist) (1839–1914), English entomologist
- William Warren (politician) (1879–1927), Premier of Newfoundland
- William C. Warren (1836–1870), first regularly employed law enforcement officer in the city of Los Angeles
- William Fairfield Warren (1833–1929), first President of Boston University
- William H. Warren, American psychologist
- William Henry Warren (1852–1926), English-born engineer, active in Australia from 1881
- William J. Warren (born 1939), Canadian lawyer and University chancellor
- William John Finley Warren (1873–1963), politician in Saskatchewan, Canada
- William K. Warren Sr. (1897–1990), American businessman and philanthropist of Tulsa, Oklahoma
- William T. Warren (1877 - 1962), American architect
- William W. Warren (1834–1880), American Representative from Massachusetts
- William Whipple Warren (1825–1853), Ojibwa historian
- Bill Warren (baseball) (1884–1960), American baseball player
- Bill Warren (businessman), American corporate human resource executive
- Bill Warren (communist) (1935–1978)
- Bill Warren (film historian and critic) (1943–2016), American film historian and critic