William Brennan
# William Brennan

William Brennan may refer to:

* William Brennan (Australian politician) (1865–1937), member of the New South Wales Parliament
* William Brennan (baseball) (born 1963), American baseball pitcher
* William C. Brennan (1918–2000), New York politician and judge
* William J. Brennan Jr. (1906–1997), justice of the United States Supreme Court
* William John Brennan (1938–2013), Australian Roman Catholic bishop
* William Joseph Brennan (bishop) (1904–1975), Roman Catholic priest in Australia
* Will Brennan (born 1998), American baseball player
* Willis Brennan (1893–1950), American football player
* Willy Brennan (died 1804), Irish highwayman
* Bill Brennan (umpire) (1880–1933), Major League Baseball umpire and college football coach
* Bill Brennan (boxer) (1893–1924), American boxer
* Bill Brennan (activist) (born 1968), candidate for Governor of New Jersey in 2017
* Bill Brennan (journalist), American sports journalist
* Billy Brennan (born 1934), British ice hockey player
