A dangerous, probably villainous knight located in the general neighborhood of the castle La Beale Regard, Sir Malgrin is mentioned in the same breath with Breuse Sans Pitie:
Then [Mark] sent unto Queen Morgan le Fay, and to the Queen of Northgalis, praying them in his letters that they two sorceresses would set all the country in fire with ladies that were enchantresses, and by such that were dangerous knights, as Malgrin, Breuse Saunce Pité, that by no means Alisander le Orphelin should escape.
In the next chapter, Alisander meets a chatelaine who asks him to joust for her sake with her neighbor, Sir Malgrin, who
will not suffer me to be married in no manner wise for all that I can do, or any knight for my sake.
Alisander and Malgrin jousted and fought on foot for
three hours, [and] never man could say which was the better night. ... But this Malgrin was an old roted [practised] knight, and he was called one of the most dangerous knights of the world to do battle on foot, but on horseback there were many better.
During a lull in the fight, the felonius Malgrin told Alisander,
Wit thou well ... for this maiden's love, of this castle, I have slain ten good knights by mishap; and by outrage and orgulité [pride] of myself I have slain ten other knights.
Alisander at last ended Malgrin’s career by smiting off his head. As for the chatelaine, she asked Alisander to give her in marriage to her old sweetheart, Sir Gerine le Grose, who lived in that area. Alisander obliged.
See also
Mark of Cornwall | The Legend of King Arthur
Morgan Le Fay | The Legend of King Arthur
Queen of Northgalis | The Legend of King Arthur