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.

Especially in the early period, a great portion of the dynasty's wealth, probably the majority, came from the international slave trade, both as slavers themselves and from the taxation of it,[5] for which they were infamous in their time.

[6] One of the greatest dynasties of the Viking Age, the Uí Ímair were at their height a fearsome and wide-reaching power in the British Isles and perhaps beyond.

[7] Like the contemporary Rurikids in the East they ultimately integrated with the native population but their impact on the histories of Scotland and Ireland are still visible through the cities they founded and the Norse-Gael descendants they left behind.

[9] The following list contains only members mentioned in the Irish annals and other reliable and semi-reliable sources, such as the Cogad Gáedel re Gallaib, and among those only the ones who can be placed in the pedigree with relative confidence.

Among recent developments in scholarship it has been argued that the historical king of Northumbria contributing to the character of Eric Bloodaxe was actually an Uí Ímair dynast.

Ivar of Limerick (died 977), and surnamed Ua hÍmair, features prominently in the early 12th century saga Cogad Gáedel re Gallaib, although he appears less in the annals, which are lacunose and in general poorer for western Ireland.

In any case he and/or the Waterford dynasty are probably survived today through intermarriage with the O'Donovan family, verifiably associated with both and known for their use of Uí Ímair dynastic names in medieval times.

It is also periodically claimed that some of the family may even be male line descendants of Ivar of Waterford, a variant of which (through his son Donndubán) actually appeared in the Encyclopædia Britannica for a few decades.

Nevertheless, dense clusters of given names strongly associated with the Norse dynasty can be found in notionally Gaelic families, in the great genealogical compilations of Dubhaltach Mac Fhirbhisigh and Cú Choigcríche Ó Cléirigh, and in various other sources.

This section, specifically focused on the pedigrees and doings of the Norse families of Ireland, was still in existence in the 17th century, as reported by Mac Firbis himself, but has since become lost.

Godred's descendants, although vassals of the Kings of Norway, continued to rule into the 1260s, the last being Magnús Óláfsson (to 1265), or briefly his son Guðrøðr (1275).

[20] Their founder Somerled married Ragnhild, daughter of Olafr Godredsson, King of Mann and the Isles and son of Godred Crovan.