The winter wren is a very small North American bird and a member of the mainly New World wren family Troglodytidae. The species contained the congeneric Pacific wren of western North America and Eurasian wren (Troglodytes troglodytes) of Eurasia until they were split in 2010.

Wrens are a family of brown passerine birds in the predominantly New World family Troglodytidae. The family includes 88 species divided into 19 genera. Only the Eurasian wren occurs in the Old World, where, in Anglophone regions, it is commonly known simply as the "wren", as it is the originator of the name. The name wren has been applied to other, unrelated birds, particularly the New Zealand wrens (Acanthisittidae) and the Australian wrens (Maluridae).