William James Harrington was a politician in Manitoba, Canada. He served in the Legislative Assembly of Manitoba from 1915 to 1920, as a member of the Liberal Party.

A resident of Dauphin, Manitoba, he was elected to the Manitoba legislature in the 1915 provincial election to represent the Dauphin constituency. He defeated Conservative incumbent William Buchanan by 102 votes.^{[citation needed]} The Liberals won a landslide majority in this election, and Harrington served as a backbench supporter of Tobias Norris's government for the next five years.

He was defeated in the 1920 provincial election, losing to Labour candidate George Palmer by 422 votes.