The Uí Ímair (Irish: [iː ˈiːwəɾʲ] ; meaning ‘scions of Ivar’), also known as the Ivar dynasty or Ivarids, was a Norse-Gael dynasty which ruled much of the Irish Sea region, the Kingdom of Dublin, the western coast of Scotland, including the Hebrides and some part of Northern England, from the mid 9th century.
The dynasty lost control of York in the mid 10th century, but reigned over the other domains at variously disputed times, depending on which rulers may be counted among their descendants. This has proved a difficult question for scholars to determine, because reliable pedigrees do not survive. Additionally, for between three and four decades, the Uí Ímair were overkings of the Kingdom of Scotland itself, distinct from the Kingdom of Strathclyde, of which they may also have been overkings, and later briefly the Irish province of Munster, dominated from Waterford, and later still, briefly the English kingdom of Mercia. In the west of Ireland, the Uí Ímair also supplied at least two kings of Limerick, from which they may have attempted to conquer Munster again.