|Member of the Western Australian Parliament
|Preceded by||Ross Hutchinson|
|Succeeded by||Colin Barnett|
|20th Leader of the Opposition (Western Australia)|
|Preceded by||Ray O'Connor|
|Succeeded by||Barry McKinnon|
|Agent-General for Western Australia|
|Born||William Ralph Boucher Hassell
1943 (age 71–72)
|Political party||Liberal Party of Australia|
|Alma mater||University of Western Australia|
William Ralph Boucher Hassell, best known as Bill Hassell, (born 1943) is an Australian former politician who was Leader of the Opposition in Western Australia during the mid-1980s. He was a member of the Western Australian Legislative Assembly seat of Cottesloe between 1977 and 1990.
- "Alumni - Graduates - Bill Hassell (1965)". University of Western Australia. Retrieved 9 November 2012.
- "A numerical listing of Members of the Legislative Assembly since 1890". Parliamentary Library Western Australia. Parliament of Western Australia. October 2012. p. 9. Retrieved 9 November 2012.
- "Leaders of the Opposition from 1905". Parliamentary Library Western Australia. Parliament of Western Australia. 21 March 2012. Retrieved 9 November 2012.