William Baker (1789 – May 1866) was a businessman and political figure in Lower Canada.
He represented Missisquoi in the Legislative Assembly of Lower Canada from 1854 until the suspension of the constitution in 1838.
He was born in Petersham, Massachusetts, the son of Joseph Baker and Maria "Molly" Stevens, and came to Dunham in Lower Canada in 1799 with his family.
His son George Barnard served in the Quebec assembly and the Canadian House of Commons and Senate.
His grandson George Harold Baker was a member of the Canadian House of Commons.