John Baker (January 17, 1796 - March 10, 1868) is the namesake of the towns of Baker Lake (Lac Baker) and Baker Brook, New Brunswick. He was a successful sawmill and gristmill businessman who became a well-known activist in the region during the 19th century. Baker was instrumental in the Aroostook War, a boundary dispute that established the international border between New Brunswick, Canada and the state of Maine, with the Webster-Ashburton Treaty.

Baker's name is indissolubly interwoven with the boundary controversy. He had homes on both sides of the disputed territory, defied the officers of New Brunswick in many ways and was twice arrested and imprisoned in the Fredericton jail, where a statue and plaque today recognize his imprisonments and his contributions to the boundary settlement. The last time that he was incarcerated was when he was indicted, tried and sentenced for sedition and conspiracy against the King of England on May 8, 1828.

Baker operated a gristmill and a sawmill on the north bank of the St. John River, and was the leading American in the disputed territory. He was dissatisfied with the official borders, and in 1827 declared his village to be capital of the "American Republic of Madawaska". Though he was American by birth, Baker ultimately settled in Canada after his imprisonment by the Crown and died at his home in the Baie des Chaleurs region of New Brunswick in 1868.