Politician and radical. Born and educated in Dundee, Mackenzie lived in Alyth before emigrating to Canada (1820). Mackenzie published an influential newspaper, the Colonial Advocate in Toronto. He was elected to the Provincial Parliament (1828) and became Toronto's first Mayor in 1834. He led a radical force for Canadian independence, which tried to seize power in 1837, resulting in his flight to the USA. There he was imprisoned for flouting US neutrality laws. He returned to Canada in 1849, becoming a Member of Parliament (1851-8).
Mackenzie is buried in Toronto. His grandson William Lyon Mackenzie King served as the 10th Prime Minister of Canada between 1935 and 1948.