Sturlunga saga (often called simply Sturlunga) is a collection of Icelandic sagas by various authors from the 12th and 13th centuries; it was assembled ca. 1300. It mostly deals with the story of the Sturlungs, a powerful family clan during the Sturlungaöld period of the Icelandic Commonwealth.
Sturlunga saga begins with the legend of Geirmundr heljarskinn, a regional ruler in late 9th century Norway, who moves to Iceland to escape the growing power of King Harald Finehair. The more historical sagas commence in 1117 with Þorgils saga ok Hafliða. Other sagas included in the collection are Sturlu saga, Prestsaga Guðmundar Arasonar and Íslendinga saga, which constitutes almost half the Sturlunga saga and covers the period 1183–1264.
Sturlunga saga is the main source of Icelandic history during the 12th and 13th centuries and it was written by people who experienced the internal power struggle which ended in Iceland's loss of sovereignty and submission to Norway in 1262.