Vulgate VII has a Sebille who seems, as nearly as I can make it out, to be the pagan queen of Sarmenie, and who may have had an affair with Sagremor (Sagramore), who was her prisoner for a while and through whom she was converted and baptized.
A knight called Le Noir Chevalier Fae appears as either her consort or her enemy - I suspect the former, but could not be quite sure from the text.
Sebille seems to have jouneyed to Britain with a company of knights armed in black, and she may possibly have been a warrior queen.
Lioines | The Legend of King Arthur
Sebile | The Legend of King Arthur