Sébile, Sedile, Sibile
According to Vulgate V, Sebile and Morgan le Fay were the two women most proficient in magic after the Damsel of the Lake.
Instead of Malory’s Queens of Gore (Morgan), Norgales, Eastland, and the Out Isles, the Vulgate account of Lancelot’s kidnaping has Morgan, Sebile, and the Queen of Sorestan as the abductresses. According to Phyllis Ann Karr are the Queens of Eastland and Sorestan probably identical; thus Sebile may be the Queen either of Norgales or the Out Isles.
Possibly, since Malory names Ryons as king of “Northgalis and Many Isles”, the Queen of Norgales and the “Out Isles” were originally one and the same character, and Malory or some scribe between him and the older versions mistakenly split her in two.
See also
Sebille of Sarmenie | The Legend of King Arthur