In January 1805, the estate of Simon McTavish leased the seigneury of Terrebonne for a period of 12 years to Henry Mackenzie (1781- 1832), an agent of the seigneury since 1803. Mackenzie then joined forces with McTavish's former partners, his brother Roderick Mackenzie (c. 1761-1844) and the lawyer turned merchant, Jacob Oldham (c. 1768-1824), to form a company that would evolve under the name Mackenzie, Oldham and Co. l’Île-des-Moulins had become a pre-industrial complex in Terrebonne managed by MacKenzie, Oldham, and Co., and equipped with a forge, a bakery, and various types of mills. The mills produced goods for sale but were also used by the citizens of Terrebonne to grind their flour and cut their wood. In 1832, the seigneury was put up for auction and was bought by Joseph Masson, a wealthy Montreal merchant.

Robert Mackenzie is a Professor Emeritus in the Department of Biochemistry, McGill University. Mackenzie recieved his PhD from Cornell University and did a postdoctoral fellowship at Berkeley. Mackenzie joined the McGill Group in Medical Genetics in 2001, where he was particularly interested in folate-mediation in mitochondrial DNA.

Roderick Charles Mackenzie (or Charles Roderick Mackenzie) was born in 1816 and became a lawyer in Montreal.

Roderick Mackenzie was born in 1761 in Achiltibuie, Scotland, to Alexander Mackenzie of Achnaclerach and Catherine Mackenzie. Mackenzie moved to Quebec in 1784 and died in 1844 near Terrebonne, Quebec. Mackenzie’s family (brothers, cousins, and in-laws) were all involved in the fur trade, and he worked as a clerk and assistant for his first cousin Alexander Mackenzie. Mackenzie travelled to the northwest and established Fort Chipewyan and set up a library for the employees of the North West Company in Athabasca. While there, he married an unknown Indigenous woman “à la façon du pays” and had three to four children with her. His daughter Nancy, from this marriage, married a fur trader named John George McTavish. Nancy’s biography can be found linked to Mackenzie’s biography in the Dictionary of Canadian Biography, in which describes the typical life and treatment for Indigenous women at the time. Mackenzie served as lieutenant-colonel in the Terrebonne Militia and was appointed with the Legislative Council of Lower Canada. He was also appointed as Justice of the Peace for the “Indian Territories” (now known as south of the Great Lakes between the Mississippi and Ohio Rivers), and later for Montreal, Trois-Rivières, Gaspé, and Saint-François in Quebec. Mackenzie was a commissioner for various construction jobs (primarily of bridges and schools) and was a member of both the Literary and Historical Society of Quebec and the American Antiquarian Society and was a fellow of the Royal Society of Northern Antiquaries at Copenhagen. Mackenzie was accredited with the authorship of the introduction of his cousin Alexander Mackenzie’s book titled Voyages from Montreal, which gives an overall account of the history of the fur trade. He was also a member of the Beaver Club, a dining club for men who had influence in the fur trade.

Donald Mackey was born in 1921 in Brockville, Ontario, and died on February 9, 1993, in Montreal. He moved to Montreal in 1935 to complete elementary and secondary school, and later studied music with Alfred Whitehead. From 1939 to 1945, he served in the Royal Canadian Air Force during the Second World War. In 1947, Mackey was invited to become the organist and choir master of the Church of the Messiah in Montreal, later becoming the Director of Music, which he did until 1965. From 1953 to 1960, he worked as a music teacher at Westmount High School. Mackey received a Bachelor of Music from Trinity College, University of Toronto in 1954, and studied there with Healy Willan. On May 1, 1956, he formed the choir known as the Renaissance Singers of Montreal. From 1956 to 1976, Mackey and the Renaissance Singers presented 129 radio broadcasts, made two TV appearances, gave nine public concerts, and collaborated with the National Film Board on a video recording. From 1960 to 1990, Mackey was employed at McGill University as University Organist, Assistant Professor, Secretary of the Faculty of Music, Director of the Faculty of Music Choir, and Supervisory Officer in the Conservatorium of Music. Additionally, he founded the McGill Organ and Harpsichord Summer Schools from 1966 to 1971 and from 1973 to 1975, he directed the McGill Summer Music Camp. Mackey went on sabbatical leave from McGill in 1978 to conduct research that led to the installation of a French classical organ in Redpath Hall. In 1981, he became Chair of the committee responsible for organizing the Symposium L’orgue à notre époque in honour of the installation of the French Classical Organ for Redpath Hall. That same year, Mackey was appointed Director of Music at the Church of St. John the Evangelist. McGill University Press published Mackey’s L'Orgue à Notre Époque: Papers and Proceedings of the Symposium in 1981. In 1984, Mackey facilitated the installation of the Memorial Organ in the Church of St. John the Evangelist. From 1984 to 1986, he served as National President of the Royal Canadian College of Organists. In 1987, he was named University Organist Emeritus of McGill. From 1987 to 1992, Mackey was the founder and president of the Montreal Chapter of the Prayer Book Society of Canada.

William MacKey (also spelled McKay) was born in 1772 in Mohawk River Valley and died in 1832 in Montreal. He was the son of Donald McKay, a former soldier with the 78th Fraser Highlanders, and Elspeth Kennedy, and he was the brother of Alexander McKay. MacKey travelled in the regions north and west of the Great Lakes and traded along the Menominee River and in Portage la Prairie. In the northwest, he married an Indigenous woman named Josette Latour, who later married North West Company trader John Haldane. In 1808, MacKey married Eliza Davidson, the daughter of Judge Arthur Davidson and Jane Fraser. They had two sons, one of whom survived infancy. MacKey’s duty as deputy superintendent in the North West Company was to advise Indigenous tribes to cultivate a harmonious relationship with the Americans. In Drummond Island (Michigan), he held a series of councils with Indigenous peoples throughout 1817 and 1818 and attempted to implement Britain’s post-war “Indian policy,” which was to reduce “His Majesty’s Indian Allies” from “warriors to wards.” MacKey served as a superintendent of Indian Affairs in Drummond Island from 1820 to 1828 and oversaw the first stages of the reserve system’s development in Upper and Lower Canada.