Joseph Leonard O'Brien (November 10, 1895 – June 18, 1973) was a Canadian politician and businessman.
By profession he was a lumber merchant, operating a small sawmill in South Nelson.
In 1940, he was elected to the House of Commons of Canada for the riding of Northumberland.
A monument stands in the national park on the island in his honour.
His remains rest at Malcolm Cemetery of St. Patrick's Church in Nelson-Miramichi, Miramichi, New Brunswick, Canada.