Agwisance, Agwisaunce, Angis, Angins, Anguins, Aguisant, Anguisant, Anguisel, Anguisshe, Angwish, Hanguin, Languis, Lenvis
King of Ireland and one of the eleven rebel kings at the beginning of Arthur's reign, but later apparently became a companion of the Round Table, being listed in Malory XIX, 11. Married to Lotta or Isolde, father of La Beale Isoud in the Prose Tristan and in Malory.
Anguish used to exact tribute from King Mark. When Mark finally refused tribute, Anguish chose his brother-in-law (or nephew), Sir Morholt (Marhaus), a champion. Mark's champion was Tristram, who killed Marhaus and freed Cornwall from Anguish's truage, but got a poisoned wound from Marhaus' sword and finally had to come to Anguish's court in disguise to be healed. Anguish became Tristram's friend, and, when Tristram's disguise was uncovered and the Irish queen tried to kill him, Anguish himself excused his brother-in-law's death and sent Tristram away with kind words.
Later, when Bleoberis and Blamore de Ganis (Blamor of Gannes), Lancelot's cousin, summoned Anguish to Arthur's court on a charge of treacherously murdering their cousin, Tristram came along by chance in time to fight as Anguish's champion and win his acquittal. This expedited Tristram's errand of seeking La Beale Isoud to be Mark's bride; Anguish only regretted that Tristram did not ask her for himself instead. Anguish had a dream portending Tristan's affair with Isolde, but still handed his daughter over when Tristan came to collect her for King Mark of Cornwall.
His name seems to be genuinely Irish in origin, a form of Oenghus. Surprisingly, at the time in question, a King Oenghus mac Nad Fraích is thought to have been reigning at Cashel, in the south of Ireland. It appears that his name may be a translational error from the original Gaelic into Old English. There may be some confusion with the Scottish King Auguselus in Geoffrey; this name is also found in the form Anguisel.
It's also suspected that King Anguish of Ireland is to be identified with King Anguish of Scotland (Angusel), though some scholars have suggested a connection with an historical Irish king named Ķengus. His counterpart in Gottfried von Strassburg is Gurmun. Malory, perhaps conflating him with Angusel, says that he was one of the kings who rebelled against Arthur, and was defeated with his comrades at Bedegraine. Tennyson gives a similar account, saying that he joined with Uriens in an invasion of Carmelide (Cameliard).
We could probably assume that Agwisance (which P.A. Karr calls him) must have ruled from one of the areas of Western Wales probably along the southern coast still controlled by Irish settlers but could be from the northwestern countries controlled by the Scotti.
Daughter: La Beale Isoud
Son or nephew?: Lanceor
Father-in-law: King Marhalt
Cousins: Lady of the Launds, Laheduman of Muntane