Sir Gawain encounters two women when he arrives at Bertilak's mysterious castle: Bertilak's wife, and an old woman. The poet describes the two women as “unlike to look upon . . . / For if the one was fresh, the other was faded” (950–951). The difference between the two women is further highlighted by their juxtaposing dress: Bertilak's wife wears beautiful, revealing clothing while the older woman is covered in fabric from head to toe. The old woman’s excessive garments symbolize her hidden nature, but Sir Gawain does not notice this at the time. Instead, struck with the younger woman’s beauty, Sir Gawain does not pay much attention to the older woman and overlooks her in favor of Bertilak’s comparatively alluring wife.

However, by the end of the poem, Sir Gawain and the reader both learn that he was too quick to disregard the old woman. The Green Knight reveals that the old woman is actually Morgan le Fay, or Morgan the Goddess, who deals in “rare magic” (2447). The Arthurian tradition typically portrays Morgan le Fay as a powerful sorceress, trained by Merlin, as well as the half-sister of King Arthur. As she often does in Arthurian literature, Morgan appears in Sir Gawain and the Green Knight as an enemy of Camelot, one who aims to cause as much trouble for her half-brother and his followers as she can. Sir Gawain learns that everyone from the Green Knight/Bertilak (bewitched to look like two different people) to Bertilak's wife are merely pawns in Morgan’s scheme to frighten Queen Guinevere to death. Essentially, Morgan le Fay has controlled the poem’s entire action from beginning to end. Sir Gawain and the Green Knight’s Morgan le Fay teaches readers a valuable lesson: appearances can be deceiving. Sir Gawain disregards the old woman and reserves his fear and veneration for more obviously formidable individuals such as King Arthur, the Green Knight, and Bertilak and his wife. However, by the end of the poem, the deceptively weak and insignificant old woman is revealed to be the most powerful person in the text.