Fairy Loup is a waterfall located on Byre Burn, a tributary of River Esk, in Dumfries and Galloway, Scotland.
The waterfall's name originates in a local legend of "a fairy having leaped from one side to the other", and is an example of a regional tradition of associating small streams with fairies. This waterfall was one of several features near Langholm described in the poetry of Hugh MacDiarmid.
A 14.5km (09miles) loop trail passing through Canonbie and Rowanburn gives access to the waterfall. Fly-tipping has been a problem in the area.