William Carson McBrien (12 January 1889 – 18 June 1954) was a Canadian business owner and civic administrator.

He began a hardware business at age 15 with his older brother Fred, a future city council alderman and member of the Ontario Legislature.

On his return to Canada, he worked in the real estate business, and became active in civic affairs.

He ran in Toronto Southwest B as a Conservative in the 1919 provincial election but lost to the Liberal John Ramsden.

During the Second World War, he served in Canada as a Lieutenant-Colonel, commanding a reserve unit of the Royal Canadian Engineers.