Njáll Þorgeirsson (Icelandic: Njáll son of Þorgeir) was a 10th century Icelandic lawyer who lived at Bergþórshvol and is one of the main protagonists of Njáls saga, a medieval Icelandic saga.
Njáll was the son of Þorgeir "gollnir" Ófeigsson. His paternal grandfather had become ill with the king and therefore decided to leave but as he had prepared and was about to leave the king's errandmen came to him and took his life.
After that his grandmother and their children and her brother leave to Iceland. Njals saga does not in important events contradict other sources but in details such as genealogy it sometimes contradicts the book of settlements which is then thought more trustworthy.
Njáll lived in Bergþórshvoll in Landeyjar and was married to Bergþóra Skarphéðinsdóttir. He is described as a kindly, wealthy non-violent and handsome man, but beardless, suffering from the peculiar defect of not growing any facial hair. He was a great lawyer — supposedly unequalled in wisdom and predictive powers — and solved the problems of every man who came to him for counsel. He was a close friend of Gunnar Hámundarson of Hlíðarendi.
After his sons become involved in a dispute, the farmstead at Bergþórshvol is surrounded by a hundred men and put on fire. By then, Njáll is an old man and is offered to leave. He chooses to stay and dies in the fire with the rest of his family — hence Njál's saga is often called "Brennu-Njáls saga", which means "the saga of Burning Njáll".