Glen Brittle (Gleann Breadail in Scottish Gaelic) is a large glen in the south of the Isle of Skye, in Scotland. It runs roughly south to north, along the River Brittle, which has its mouth at Loch Brittle (a sea loch). The glen is bounded on the east by the main Black Cuillin ridge, the largest mountains on Skye. The name is probably derived from old Norse Bred Dal ("broad valley") with the Gaelic glean ("valley") being prefixed later.