Brock is a township in the Regional Municipality of Durham, Ontario, Canada. Brock Township is also a former municipality and geographic township prior to the amalgamation that formed the current municipality. The Trent–Severn Waterway forms part of the northern border of the municipality, which enters Lake Simcoe through Ramara Township. There are five locks in Brock. Thorah Island in Lake Simcoe is within the municipal boundaries of Brock.