John Sylvester Aloysius Sinnott (9 May 1905 – 10 August 1960) was a Liberal party member of the House of Commons of Canada.
He was born in Saint-Ouens, Manitoba and became a farmer and implement agent.
Sinnott attended school in Saint-Ouens, then studied at Manitoba Agricultural College.
This proved unpopular in his riding and he was defeated in his attempt to win his party's nomination for the following election.
He then reversed his previous position and led a fight in the House of Commons against the creation of pensions for Members of Parliament and introduced a bill to make MP salaries fully taxable.