Alan Aylesworth Macnaughton (July 30, 1903 - July 16, 1999) was a Canadian parliamentarian and Speaker of the Canadian House of Commons from 1963 to 1966.

Macnaughton was born in Napanee, Ontario and educated at Upper Canada College. He studied law at McGill University and began a law practice in Montreal where he served as a Crown Attorney from 1933 to 1942.

Macnaughton first won a seat in the Canadian House of Commons in the 1949 Canadian election when he was returned as a Liberal MP for the riding of Mount Royal. Macnaughton served as Chairman of the Public Accounts Committee after the 1958 Canadian election and his performance in that position led to the newly elected Liberal government nominating him for the position of Speaker following the 1963 Canadian election.

Macnaughton presided over a House of Commons led by a minority government in which no party had control of the House resulting in long and bitter debates making it a challenge for any Speaker to maintain order.

Acrimonious debates included that over the adoption of a new Canadian flag as well as the Munsinger Affair and other scandals. As Speaker he attempted to bring in procedural reforms to make Parliament more efficient. He established four subcommittees of the Special Committee on Procedure and Organization, each chaired by a member of a different political party.

The result of this process were recommendations for new procedures of time allocation in debates, a new committee structure, the abolition of the right to appeal rulings of the Speaker, research budgets for members and other changes most of which were ulitmately implemented.

During the Flag Debate, Macnaugton set a precedent by allowing the motion to be split into two and allow separate motions on making the Maple Leaf the new flag and using the Union Jack as a symbol of Canada's membership in the British Commonwealth. This was the first time a Speaker took it upon his own authority to split a motion. Macnaughton did so in hopes of facilitating debate and calming the House.

Macnaughton did not contest the 1965 Canadian election and retired from electoral politics. He was succeeded as MP for Mount Royal by Pierre Trudeau.

In 1966, Macnaughton was appointed to a seat in the Canadian Senate by Lester Pearson and served in that body until his retirment in 1978