The Fair Isle wren (Troglodytes troglodytes fridariensis) is a small passerine bird in the wren family. It is a subspecies of the Eurasian wren endemic to Fair Isle, Shetland, Scotland. It was first described by Kenneth Williamson in 1951.
The Fair Isle wren is darker and larger than the mainland form of the winter wren, though not as dark as another insular subspecies, the Shetland wren, T. t. zetlandicus.
Fair Isle is a small island, 7.68 km2 in area, and the population of the wren is tiny, varying from ten to fifty pairs, breeding mainly on boulder beaches.