Nentres is best known as the husband of Princess Elaine of Tintagel. The couple raised Elaine’s little sister, Morgan le Fay, and later had their own children, Sir Galescalain & Lady Elaine Junior. Nentres was amongst the kings who doubted Arthur’s right to the throne and rebelled against him at the commencement of his reign. He pledged 5,000 mounted men to the revolt and fought valiantly at the Battle of Bedegraine. When the rebel kings had to postpone their seditious actions in order to repel the Saxon attacks on Wandesborow, Nentres was place din command of the city of Wyndesan (possibly Windsor). His wife, Elaine, was kidnapped by the Saxons by rescued by the lady's nephew and Arthur’s man, Sir Gawain. The king thus refrained from entering the second phase of rebellion and felt obliged to make peace with Arthur. He helped crush the enemy at the Battle of Clarence and followed his brother-in-law on his continental campaigns. Nentres was particularly respected for striking down King Alifatima of Spain and was made a Knight of the Round Table for his services to the Crown.

The name Nentres may be an extreme corruption of Emyr Llydaw (Emperor of Brittany), the commonly used name for King Budic II of Brittany. A number of sources indicate that he was the husband of one of King Arthur’s half sisters. Nentres’ kingdom of Garlot probably stems from Caer-Lot (Fortress of Lot) and is really the territory of Queen Elaine’s brother-in-law, King Lot of Orkney.