Blácaire mac Gofraid

Blácaire mac Gofraid (Old Norse: Blákári Guðrøðsson [ˈblɑːˌkɑːre ˈɡuðˌrøðsˌson]; died 948) was a Viking leader who ruled Dublin in the 10th century. He succeeded his brother Amlaíb mac Gofraid as king in 939 after the latter left Dublin to rule Northumbria. In the early years of his reign Blácaire led raids on important Christian sites at Clonmacnoise and Armagh, but repeated attacks by the Irish of Leinster in 943 and 944 led to the sack of Dublin. A year later Blácaire was replaced as King of Dublin (perhaps because of his inability to defend the city) by his cousin Amlaíb Cuarán, who had succeeded Blácaire's brother in Northumbria in 941, but had been driven out in 944.

Amlaíb allied with Congalach Cnogba, overking of Brega and the Southern Uí Néill, one of those Irish kings who led the attack on Dublin in 944, and was possibly subject to him. They fought together against the Northern Uí Néill in 947, but they were defeated and the Dubliners suffered many casualties. That year Blácaire was able to regain the kingship from Amlaíb and reversed the alliance with Congalach. Vikings raided into Congalach's lands in 948, leading to a battle between the Dubliners and the Southern Uí Néill in which Blácaire was killed. With his rival dead, Amlaíb left for England to regain Northumbria and his brother Gofraid mac Sitriuc was made king in Dublin.