Ímar (Ívaar) (d. 1000), grandson of Ragnall and king of Waterford, belonged to a junior line of the Hiberno-Scandinavian dynasty known as Uí Ímair. This lineage, which ruled Dublin, claimed descent from Ímar (qv) (d. 873), king of Dublin. The parentage of Ímar of Waterford is not recorded, but his grandfather Ragnall (qv) (d. 921) had reigned over the Waterford vikings before his accession to the kingship of York. It is not clear that Ímar, like his cousin Amlaíb (Óláfr) Cuarán (qv), was a convert to Christianity, but he probably had an Irish Christian wife, as one of his sons was named Gilla-Pátraic. He also had a son named Ragnall, and Donnaman son of Ímar was perhaps another of his sons.
By about 980 Ímar held the kingship of Waterford and was involved in a bitter feud with his Dublin-based kinsmen. His plundering of Kildare (982), shortly after the death of Amlaíb Cuarán, should probably be seen as an attack on Dublin's sphere of influence. The following year he was defeated in northern Leinster, along with his ally Domnall Clóen of Uí Dúnchada, nominal overking of the Leinstermen, by the new king of Dublin, Glún-Iarainn son of Amlaíb Cuarán, supported by the powerful king of Tara, Máel-Sechnaill (qv) son of Domnall. The casualties in this engagement included his son, Gilla-Pátraic.
In the years that followed, the fortunes of war alternated. In 990 a son of Ímar, probably Ragnall, abandoned Waterford – the same year that a Norse fleet attacked Roscarberry on the coast of Co. Cork. Then, in 994, Ímar gained control of Dublin for a while as its reigning king, Sitriuc Silkbeard (qv) son of Amlaíb Cuarán, was driven from the town. Soon afterwards, however, as the Annals of Ulster report, Ímar's son Ragnall was killed by ‘Murchad’; perhaps Máel-mórda (qv) (slain 1014), son of Murchad of Uí Fháeláin, is intended. In 996 Donnaman son of Ímar killed the king of neighbouring Osraige, Gilla-Pátraic son of Donnchad, before being slain in revenge by the Leinstermen.
Ímar himself died in 1000, apparently of natural causes. It seems that at least three of his grandsons reigned as kings of Waterford; his successor Ragnall, killed in 1018 by members of the Co. Cork dynasty of Uí Liatháin, and the latter's brother Sitriuc, slain by the Osraige in 1022, were probably sons of Gilla-Pátraic. Ragnall, a son of the Ragnall slain in 994/5, was put to death in Dublin by Sitriuc Silkbeard in 1035.