Lough Craghy (), also locally known as Tully Lake, is a freshwater lake in the northwest of Ireland. It is located in north County Donegal in the Rosses fishery.
Lough Craghy is east of Dungloe. The lake drains westwards into Dunglow Lough.
Fish species in Lough Craghy include sea trout. These trout are seasonal, present in summer only.