William Clarke McKinnell (September 29, 1873^[1] – October 27, 1939^[2]) was a politician in Manitoba, Canada. He served in the Legislative Assembly of Manitoba from 1920 to 1936.^[1]

McKinnell was born in Northampton, England, the eldest son of William McKinnell and Catherine Perkins,^[3] in a family of 10 children. He was educated at Bedford Modern School from 1887 until 1889.^[3] He registered with the Pharmaceutical Society of Great Britain as an apprentice to his father, a Northampton chemist, but abandoned this pursuit^{[citation needed]} to go to Canada in 1892. By 1894 he was homesteading in Melita, Manitoba but later moved to Teulon, Manitoba where he opened the town's first store,^[3] McKinnell and Wood General Store. In 1901, McKinnell married Christina Margaret Wood.^[4] He served as chair of the school board in Teulon, Manitoba from 1907 to 1921 and was appointed as chair of the Winnipeg Suburban Municipal Board in 1925.^[3]

He was first elected to the Manitoba legislature in the 1920 provincial election. Running as a Farmer candidate, he defeated Liberal incumbent Arthur Lobb^[1] by a single vote (978 to 977) in the Rockwood constituency. McKinnell served with the Independent-Farmer caucus in the parliament which followed.

He ran for re-election in the 1922 election as a candidate of the United Farmers of Manitoba (UFM),^[1] and was easily returned over candidates of the Liberal and Conservative parties. The UFM unexpectedly won a majority of seats in this election, and formed government as the Progressive Party. McKinnell served as a backbench supporter of John Bracken's government.

McKinnell was easily re-elected in the campaigns of 1927 and 1932. He was defeated in the 1936 election, losing to Conservative Mungo Lewis^[1] by 383 votes.

After retiring from politics, he worked as a supervisor of municipalities.^[4] McKinnell died at home in Winnipeg at the age of 66.^[2]