Robert Henry McGregor, PC (March 1, 1886 – October 25, 1965) was a long-time Canadian parliamentarian. MacGregor was a contractor and horticulturalist by profession. He was first elected to the House of Commons of Canada in the 1926 federal election and sat continuously in the chamber for thirty-six years until his defeat in the 1962 federal election when he was 79 years old. Though never a member of Cabinet, he was elevated to the Queen's Privy Council for Canada on December 21, 1960 on Diefenbaker's recommendation in recognition of McGregor's long tenure of service.