William Alexander McGillivray (October 14, 1918 – December 16, 1984) was a lawyer, jurist, and a Chief Justice of Alberta, Canada.

He served as Bencher of the Law Society of Alberta from 1958–1969, and then as its President from 1969–1970, becoming Queen's Counsel on December 31, 1957.

He practiced in Calgary with the law firm of Fenerty, McGillivray, Robertson, Prowse, Brennan, Fraser and Bell.

Once on the bench, he was known for writing many reported criminal law judgments.

During that time, he also served concurrently as Chief Justice of the Northwest Territories.