Forbes Glacier is a glacier which flows west into the northeast corner of Square Bay, on the west coast of Graham Land, Antarctica. It is 10 nautical miles (19 km) long, 4 nautical miles (7 km) wide in its central part, and narrows to 2 nautical miles (4 km) at its mouth. The lower reaches of the glacier were first surveyed in 1936 by the British Graham Land Expedition under John Rymill.