Sir Balyn, (known as Balyn The Savage in Tennyson) brother of Sir Balan, is a character mentioned in various Arthurian legends. His story is retold, along with his brother's, in The Ballad of Balyn and Balan, Book II in Thomas Malory's Le Morté d' Arthur and by Alfred, Lord Tennyson in Idylls of the King
Balyn leads a life cursed with misfortune. A knight whom he is protecting is killed by the treacherous, invisible knight Garlon. When Balyn attempts to avenge the death by tracking Garlon down to the castle of King Pellam, he gets involved in a fight, lashes out in self defence and wounds the lord of the castle, King Pellam, with the sacred spear that pierced the side of Christ. This blow is the Dolorous Stroke, which lays the waste the land and produces a wound that can only be healed when the Grail is achieved eventually by Sir Galahad.
In Malory's version of the story, Balyn wins a second sword through chivalry, and becomes known as The Knight with Two Swords. He is warned that if he keeps both swords, then he will kill the man he loves most in the world and bring about his own destruction.
Balyn rides through the Wasteland, receiving rebukes for causing such death and devastation; but as the days pass he finds himself in fairer countryside and at last arrives at a castle where he is compelled to fight with its resident defender. This defender is his brother Balan, who has earned this role against his will by killing the previous occupier of the position. Unfortunately, neither brother recognizes the other: Balan is wearing unfamiliar red armour, and Balyn has been persuaded to change his shield for a better one immediately before the duel. The brothers mortally wound each other, Balyn outliving Balan only by a few hours. They are "buryed bothe in one tombe."
In Bradley's The Mists of Avalon Balyn and Balan are foster brothers, Balan being the son of Vivianne, the Lady of the Lake. When Vivianne provides suicide assistance to Balin's mother during a long, torturous illness, Balyn is driven to madness by grief and the two foster-brothers slay each other.