Who is Guinevere?

In Arthurian legend, Guinevere was the beautiful, aristocratic queen of Britain and wife to noble King Arthur. Her father was the Scottish king Leodegran, who gave Arthur the well-known round table that served as his court's pièce de résistance. She is first mentioned as either "Guanhumara" or "Gwenhwyfar" in a number of mid-twelfth- century writings by notable British luminaries.
King Arthur is advised by his sorcerer and counselor, Merlin, not to marry her, because Merlin foresees that she will one day be unfaithful to Arthur. The prophecy proves true when she meets and falls for Arthur's chief knight, Lancelot, leading to a tragic love triangle and several battles between the two men. In Welsh, the name Gwenhwyfar actually translates to "The White Enchantress."
Modern adaptations of the centuries-old tale often portray the circumstances of Guinevere and Lancelot's romance differently. While some depict her as an innocent and naive wallflower who is manipulated into adultery by a devious Lancelot, with Arthur as her one and only true love, others present her as strong and virtuous but ultimately flawed, with her and Lancelot sharing an intimate history prior to her marriage, thereby making the intricacies of the triangle much more complex.
The tragic climax of her story occurs when Arthur's nephew Mordred, who has been left in charge of the kingdom while Arthur is away on a military campaign, plots to kill his uncle, assume control over the land, and steal Guinevere for himself. In the most popular version of the story, she hides away in the Tower of London until Arthur returns to battle Mordred, resulting in both men's deaths. Guinevere, overcome with despair, subsequently joins a convent and remains alone until her death, after which she is buried alongside Arthur.

In Arthurian legend, Guinevere is the renowned wife of King Arthur, known for both her beauty and betrayal. She is mentioned in several historical fiction and chronicle pieces, first appearing in the Historium Regum Britannie (Geoffrey of Monmouth, circa 1136) and later in famous tales such as Chrétien de Troyes' Lancelot, the Knight of the Cart (circa 1177). In the latter, Guinevere's betrayal to King Arthur is revealed through her affair with one of King Arthur's most trusted knights, Lancelot. According to legend, this results in a heated duel between Lancelot and Arthur, and ultimately Arthur's death by the sword of his own son Mordred—most notably detailed in Sir Thomas Mallory's Le Morte d'Arthur in 1485.
Despite how Guinevere's tale has changed through history, she remains a prolific character tied to legends and stories surrounding King Arthur and the Knights of the Round Table. Depending on the literary piece, she may be depicted as lovely and pure or a mere an antagonist to Arthur and his fate. But one thing is certain: Guinevere remains as one of the most recognized characters in romantic literature.

Guinevere is the wife of the legendary King Arthur. One of the most famous love triangles in history includes Guinevere, her husband King Arthur, and Lancelot--one of King Author's most trusted knights. She is known for her great beauty and her name can be translated as "The White Enchantress" in Welsh. Besides her beauty, she is represented differently throughout literature often being described as either weak and flawed or as independent and strong.
In many of the classical adaptations of the story, Guinevere and Lancelot's affair leads to the fall of Arthur. In the French adaptations Guinevere and Lancelot's affair is revealed by his enemy and sorceress Morgan le Fay. After this revelation Arthur orders Guinevere to be burned at the stake after Lancelot flees for his life. Arthur hopes Lancelot will return to save Guinevere and orders his knights to guard Guinevere and to kill Lancelot should he return. Lancelot succeeds in saving the queen but kills the brothers of a fellow knight, Gawain. Enraged by his brothers' deaths, Gawain convinces Arthur that he must go to fight Lancelot personally. Arthur leaves his kingdom with Guinevere under the care of Mordred. Mordred betrays the king by planning to marry Guinevere and take Arthur's throne.
In many stories Guinevere spends the remainder of her life in a convent following the downfall of her husband.

(The image attached is one of the most famous depictions of Guinevere knighting Sir Lancelot. It is titled "The Accolade" by Edmond Leighton, 1901)

The name Guinevere most likely refers to the wife of King Arthur, who is featured prominently in Arthurian legend. Guinevere famously has an affair with one of King Arthur's knights, Sir Lancelot. This affair eventually leads to the downfall of all three characters. When he is informed of the affair by the sorceress Morgan le Fay, Arthur orders Guinevere to be burned at the stake. She is saved by a returning Lancelot, causing Arthur to challenge him to a duel. Arthur decides to leave Guinevere in the hands of his nefarious son, Mordred, while he battles Lancelot, but when he becomes aware of a plot for Mordred to marry Guinevere himself, he returns to Britain. Arthur is killed in his battle with Mordred, and Guinevere resigns herself to a convent for the rest of her days.