Njáll Þorgeirsson (Icelandic: Njáll son of Þorgeir, the name Njáll is a Norse derivative of the Irish name Niall.) was a 10th-century Icelandic lawyer who lived at Bergþórshvoll 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 fallen out of favour with the king and therefore decided to leave but as he had prepared and was about to leave when the king's errandmen came to him and took his life.
After that his grandmother and their children and her brother left for Iceland. Njál's saga does note in important events contradict other sources but in details such as genealogy it sometimes contradicts the Landnámabók which is 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 condition 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 Bergþórshvoll is surrounded by a hundred men and put on fire. By then, Njáll is an old man and is offered the chance 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".