Bertilak's wife, the Lady of Castle Hautdesert, is never named in the poem, although she has an important role in the action. To Gawain's eyes, she is even more beautiful than Guenevere, which makes her impossibly beautiful, because Guenevere is supposed to be the most beautiful woman in the world. Not only beautiful, but charming and persuasive, she is a formidable challenge for Gawain. She persistently tries to seduce him, insisting that he live up to his reputation as the most courteous knight and teach her the ways of courtly love. From Gawain's perspective, she is a temptress, but she is later shown to be a faithful wife, because she and Bertilak conspire to test Gawain. She is clearly in command during all of their conversations, and in a reversal of the usual patterns of courtly love, she is the one initiating the relationship. Her wit and skill at wordplay shine in these exchanges, but Gawain is equally skillful in evading her requests. Although she cannot make Gawain her lover, she finally manages to entice him into a breach of faith with her offer of her green silk belt. The lady shows considerable resourcefulness in finding the chink in Gawain's armor.
Several critics have suggested that the Lady and Morgan are ultimately two aspects of the same character, rather like Bertilak and the Green Knight. The question of which character is the "real" one may not be answerable in either case.