Merrow

Irish mermaid (bas-relief, Clonfert Cathedral).
Carving of mermaid (possibly with mirror), Clontuskert Abbey

Merrow (from Irish murúch, Middle Irish murdúchann or murdúchu) is a mermaid or merman in Irish folklore. The term is anglicised from the Irish word murúch.

The merrows supposedly require a magical cap (Irish: cochaillín draíochta; anglicised: cohuleen druith) in order to travel between deep water and dry land.