Blathmin Ní Briain, also called Blathmin Ua Briain or Blathmin O'Brien, (floruit

Floruit

Floruit , abbreviated fl. , is a Latin verb meaning "flourished", denoting the period of time during which something was active...

 1103), was an Irish princess and a Norwegian Queen consort

Queen consort

A queen consort is the wife of a reigning king. A queen consort usually shares her husband's rank and holds the feminine equivalent of the king's monarchical titles. Historically, queens consort do not share the king regnant's political and military powers. Most queens in history were queens consort...

, the first spouse of King Sigurd I of Norway

Sigurd I of Norway

Sigurd I Magnusson , also known as Sigurd the Crusader , was King of Norway from 1103 to 1130. His rule, together with his brother Eystein I of Norway , has been regarded by historians as a golden age for the medieval Kingdom of Norway...

.

A marriage alliance was negotiated between Magnus and Muircheartach Ua Briain

Muircheartach Ua Briain

Muircheartach Ua Briain , son of Toirdelbach Ua Briain and great-grandson of Brian Bóruma, was King of Munster and later self declared High King of Ireland.-Background:...

, the leading king in Ireland at the time and ruler of Dublin. Sigurd was to marry Muirchertach's daughter, Blathmin. However, when Magnus was killed in Ulaid in 1103, the 14-year-old Sigurd returned to Norway, leaving his child-bride behind, and became king together with his brothers Øystein and Olav.