Etymology and usage
The English name "wren" derives from Middle English wrenne, Old English wrænna, attested (as wernnaa) very early, in an eighth-century gloss. It is cognate to Old High German wrendo, wrendilo, and Icelandic rindill (the latter two including an additional diminutive -ilan suffix). The Icelandic name is attested in Old Icelandic (Eddaic) rindilþvari. This points to a Common Germanic name *wrandjan-, but the further etymology of the name is unknown.
The wren is also known as kuningilin "kinglet" in Old High German, a name associated with the fable of the election of the "king of birds". The bird that could fly to the highest altitude would be made king. The eagle outflew all other birds, but he was beaten by a small bird that had hidden in his plumage. This fable is already known to Aristotle (Historia Animalium 9.11) and Pliny (Natural History 10.95), and was taken up by medieval authors such as Johann Geiler von Kaisersberg, but it concerns Kinglets (Regulus) and is apparently motivated by the yellow "crown" sported by these birds (a point noted already by Ludwig Uhland). In modern German, the name is Zaunkönig, king of the fence (or hedge) and in Dutch the name is winterkoning (king of winter).
The family name Troglodytidae is derived from troglodyte, which means "cave-dweller", and the wrens get their scientific name from the tendency of some species to forage in dark crevices.
The name "wren" is also ascribed to other families of passerine birds throughout the world. In Europe, kinglets are commonly known as "wrens", the common firecrest and goldcrest as "fire-crested wren" and "golden-crested wren", respectively.
The 27 Australasian "wren" species in the family Maluridae are unrelated, as are the New Zealand wrens in the family Acanthisittidae, the antbirds in the family Thamnophilidae, and the Old World babbler of the family Timaliidae.