William John Bowser (December 3, 1867 – October 25, 1933) was a politician in British Columbia, Canada. He served as the 17th premier of British Columbia from 1915 to 1916.
The son of William Bowser and Margaret Gordon, Bowser was educated at Mount Allison University and Dalhousie University. He moved to Vancouver to practice law in 1891, and after being an unsuccessful candidate in the 1898 provincial election, was first elected to the provincial legislature in the 1903 election as a Conservative. Bowser served as Attorney General in the cabinet of Sir Richard McBride from 1907 until 1915. He also served as Minister of Finance and Agriculture between October 1909 and October 1910, and then again between March and December 1915.
In 1915, he succeeded McBride as Premier. Bowser continued as leader of the opposition until he lost his seat in the 1924 election.
A river, a lake and the small community of Bowser on Vancouver Island, between Parksville and the Comox Valley, are named for Bowser.