Guinevere (/ˈɡwɪnəvɪər/ GWIN-ə-veer; Welsh: Gwenhwyfar ; Breton: Gwenivar, Cornish: Gwynnever), also often written in Modern English as Guenevere or Guenever, was, according to Arthurian legend, an early-medieval queen of Great Britain and the wife of King Arthur. First mentioned in literature in the early 12th century, nearly 700 years after the purported times of Arthur, Guinevere has since been portrayed as everything from a fatally flawed, villainous, and opportunistic traitor to a noble and virtuous lady. The variably told motif of abduction of Guinevere, or of her being rescued from some other peril, features recurrently and prominently in many versions of the legend.
The earliest datable appearance of Guinevere is in Geoffrey of Monmouth's pseudo-historical British chronicle Historia Regum Britanniae, in which she is seduced by Mordred during his ill-fated rebellion against Arthur. In a later medieval Arthurian romance tradition from France, a major story arc is the queen's tragic love affair with her husband's best knight and trusted friend, Lancelot, indirectly causing the death of Arthur and the downfall of the kingdom. This concept had originally appeared in nascent form in Chrétien de Troyes's poem Lancelot, the Knight of the Cart prior to its vast expansion in the prose cycle Lancelot-Grail, consequently forming much of the narrative core of Thomas Malory's seminal English compilation Le Morte d'Arthur. Other themes found in Malory and other texts include Guinevere's usual barrenness, the scheme of Guinevere's evil twin to replace her, and the particular hostility displayed towards Guinevere by her sister-in-law Morgan.