|This article does not cite any references or sources. (December 2009)|
Gaheris // is a character in the Arthurian legend, a nephew of King Arthur and a Knight of the Round Table. As son of Arthur's sister or half-sister Morgause and her husband Lot, King of Orkney and Lothian, he is a brother of Gawain, Agravaine and Gareth and half-brother of Mordred.
Role in Arthurian tradition 
In Thomas Malory's Le Morte d'Arthur, Gaheris is squire to his elder brother Gawain, whose fiery temper he helps moderate, before being knighted himself. He participates in the revenge killing of King Pellinore, his father's slayer, and Sir Lamorak, Pellinore's son and his mother's lover. More notorious is his beheading of his own mother, Morgause, after catching her in flagrante delicto with the youthful and handsome Lamorak, who meanwhile escapes. Believing him to be their mother's murderer, Lamorak is hunted down by all of the brothers except Gareth, and Mordred stabs him in the back. Since, in Malory, Lamorak is greater than any knight except Lancelot and Tristram, the Orkney brothers' act of revenge is deemed cowardly and a blot on their honour. When Arthur and the brothers discover Gaheris is Morgause's slayer, he is banished from court.
Despite being exiled, Gaheris appears later in the narrative—when he and his brother Gareth are accidentally killed by Lancelot during the rescue of Guinevere. Gaheris and Gareth will have nothing to do with Agravaine and Mordred's plot to entrap Lancelot and Guinevere, and when Arthur asks the brothers to help guard the Queen's execution, Gaheris and Gareth reluctantly agree, though Gawain refuses. They decline to wear armor, and Lancelot (unable to distinguish friend from foe in his blind wrath, and rush to save the woman he loves), cuts down the unarmored princes. When he is later told what happened, Lancelot is emotionally anguished, because he loved Gareth almost like a son. Gawain's fury at this outrage is terrible and the resulting feud largely destroys the Round Table.
Gaheris is often little more than a supporting character to his brothers Gawain and Gareth, with the murder of Morgause an odd exception, leading modern authors such as T. H. White (who repeatedly describes Gaheris as "dull" or "dull-witted") to attribute the act of matricide to Agravaine instead. Again, White gives his own individual interpretation to the story, depicting Agravaine as having an unhealthy love/lust obsession for his own mother. Gaheris even marries the sister of Gareth's wife Lyonors, the haughty damsel Lynette. It is likely Gaheris and Gareth were the same character in origin, as their names in French sources, Guerrehes (Gaheris, usually) and Gaheriet (Gareth, usually), are easy to confuse and adventures ascribed to the brothers are often interchangeable. Furthermore, only one brother is ever named for Gwalchmai ap Gwyar, the character from Welsh mythology traditionally identified with Gawain. This character, Gwalchafed, is a likely source for Gaheris and Gareth if Gawain did indeed derive from Gwalchmai.