Sir Launcelot in the Queen’s Chamber (1857), Dante Gabriel Rossetti
Guinevere is the Norman–French form of the Welsh name Gwenhwyfar (white phantom), which derives from from Old Celtic roots •windos (white, fair, blessed) and *sebros (magical being, phantom). Who doesn’t know Queen Guinevere is King Arthur’s wife? She’s alternately depicted as virtuous but flawed and a self-serving traitor. Many stories feature her being abducted and having an affair with Lancelot which leads to the downfall of Camelot.
You can read this post for more in-depth information and a comprehensive list of other forms of Guinevere in different languages.
Gwendolen may mean “white ring,” derived from Welsh roots gwen (fair, white, blessed) and dolen (loop, ring). She’s Merlin’s wife. Some scholars believe this name may have arisen from a misreading of the male Old Welsh name Guendoleu, which may derive from gwyn (white, blessed, fair) and dol (meadow). Other forms include Gwendolyn (English) and Gwendoline (French, British English, Welsh).
Gwynhwyfach may derive from the name Gwenhwyfar with the Welsh suffix -ach, which evokes unpleasantness. She’s Guinevere’s sister, and the probable meaning of her name seems to suggest she’s meant as an evil or unpleasant form of Guinevere.
Władysław T. Benda illustration from Uther and Igraine (1903)
Heliabel is Perceval’s sister.
Herzeloyde derives from Middle High German roots herze (heart) and leit (sorrow, grief, suffering). She’s the mother of Parzival in Wolfram von Eschenbach’s 13th century romance Parzival.
Igraine comes from the Welsh name Eigyr/Eigr, which is of unknown origin. The Latin form is Igerna. Igraine is Duchess of Cornwall and King Arthur’s mother.
Tristan and Isolde (1901), by Herbert James Draper
Iseult may be Celtic in origin, or it may derive from an Ancient Germanic name like Ishild, composed of roots is (ice) and hilt (battle). She’s an Irish princess who’s betrothed to King Mark of Cornwall, and while en route to her new country, she and Mark’s nephew Tristan accidentally drink a love potion which makes them fall in love. This sets many tragic events in motion.
Other forms of the name include Isolde (German and Scandinavian), Isolda (Latin, Dutch, Spanish, Portuguese, Catalan, Galician, Czech), Izolda (Polish, Serbian, Russian, Georgian, Sorbian, Hungarian), Isoud (Norman), Isoude (Middle English), Ísodd (Old Norse), Izold (Breton), Isalde (Middle German), Isotta (Italian), Isolt (Old French), Iseut (Norman and Old French), Isaut (Old French), Iosóid (Irish), Esyllt (Welsh), Eseld (Cornish), Yseut (Old French), Ysolt (Old French), and Yseult (modern French).
Owain Departs from Landine (pre-1898), by Edward Burne-Jones
Laudine may derive from Lot or the place name Lothian, which both have the same origin and ultimately derive from the Latin place name Leudonia (of unknown origin). She’s the Lady of the Fountain, and marries Yvain after he murders her husband.
Lunete derives from the Welsh name Eluned, which has the root eilun (idol, image, likeness). In Chrétien de Troyes’s 12th century Old French epic Yvain, the Knight of the Lion, Lunete is the Lady of the Fountain and helps Yvain. In Thomas Malory’s 15th century Le Morte d’Arthur, she appears as Lynet and marries Gaheris. Alfred, Lord Tennyson calls her Lynette. In the Welsh romance Owain, or the Lady of the Fountain, she’s Luned.
Lyonesse means “lioness” in Middle English. In Thomas Malory’s epic, the Red Knight traps her in a castle, and her sister Lynet gets Gareth to rescue her. Other forms of the name are Lionesse and Lyones.
Lyonors has an affair with King Arthur in Thomas Malory’s story and has a son by him, Borre. She’s the equivalent of Lyonesse.
Morgan-le-Fay (1863–64), by Frederick Sandys
Morgan probably derives from Old Welsh roots mor (sea) and gen (born of), not the male Welsh name Morcant (Morgan in modern times), which may have the roots mor and cant (circle). The Middle English form used by Geoffrey of Monmouth is Morgen, and the French form is Morgaine. Who doesn’t know the sorceress Morgan le Fay, King Arthur’s sister and protector?
Morgause is Queen of the Orkneys, King Arthur’s halfsister, a witch, and the mother of Mordred, Gawain, and Gareth. The original forms of her name are Orcades and Morcades. The former was the earliest known name for the Orkney Islands and probably derives from Celtic root *forko- (piglet). Orcades may have become Morcades and Morgause due to confusion with Morgan. The name sometimes appears as Margause.
Melora probably derives from Meliora, which comes from the Latin word melior (better). This name first appears in the 1696 Irish romance The Adventures of Melora and Orlando, where she’s a minor character.