The surname Crumlish (and it's variants Crimlisk and Crumlisk) is an anglicised version of the Gaelic Ó Cromruisc, meaning "drooped eye".

The name is quite unusual, and is generally only found in Derry and Donegal. The current family in Moville can be traced back, with certainty, to John Crumlish who was born in or around the townland of Mossyglen in 1800.

The earliest recorded mention of the name is with Diermond, Owen and Nile Grome Ó Cromruske in the 1609 State Pardon List. The pardons would probably have been received, after capture, for the part they played in Sir Cahir O'Doherty's uprising against the English in 1608, and his sack of Derry.