Hellawes the Sorceress
Lancelot braved the chapel to retrieve a sword and discovered that its terrifying properties were simply illusions. Hellawes appeared before him and asked him for a kiss in exchange for the sword, but Lancelot refused. It turned out that Lancelot would have perished from the kiss had he consented. Hellawes had tendencies toward necrophilia, and she would have rather had Lancelot as a dead lover than to have lived without him. Lancelot hurried away, and Hellawes died a few weeks later from sorrow.
She had a similar passion, though not so deadly, for Gawaine.
Very likely Malory's Hellawes should be identified with the Vulgate's Helaes de la Forest Perilleuse.