Njáll Þorgeirsson was a 10th-century Icelandic lawyer who lived at Bergþórshvoll in Landeyjar, Iceland. He was one of the main protagonists of Njáls saga, a medieval Icelandic saga which describes a series of blood feuds. 
Njáll was the son of Þorgeir gollnir Ófeigsson. His paternal grandfather had fallen out of favour with the king and therefore decided to leave Norway 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. Njáls saga does not in important events contradict other sources but in details such as genealogy it sometimes contradicts the Landnámabók which is thought more trustworthy. The name Njáll is a Norse derivative of the Irish name Niall.
Njáll lived in Bergþórshvoll 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 chieftain 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 was 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 Njáls saga has also been called Brennu-Njáls saga meaning "Saga of Burning Njáll".
- Børge Nordbø. "Njåls saga". Store norske leksikon. Retrieved November 1, 2019.
- Hudson, B.J (2005) Viking Pirates and Christian Princes: Dynasty, Religion, and Empire in the North Atlantic, Oxford University Press. p. 63
- "Gunnar Hámundarson was a 10th century Icelandic chieftain". spangenhelm.com. Retrieved November 1, 2019.
- "Brennu-Njáls Saga". snerpa.is. Retrieved November 1, 2019.