Who was King Arthur's daughter?

Not sure he had a daughter, most sources say he had sons. I can't remember the sources, I think it's the Welsh chronicles (or something) says he had a son named Amir that he killed for unknown reasons. His other sons include Loholt, unknown who the mother is and who has little mention in any Arthurian Legends and Mordred. Mordred is the most famous as he kills Arthur and is King Arthur's son by his half sister Morgause or Morgan. Hope I helped.

He has daughters in several modern versions. Vera Chapman's "King Arthur's Daughter" comes to mind. There is also Debra A. Kemp's House of Pendragon series, told through the point of view of Lin, Arthur and Gwenhwyfar's daughter. Although Lin doesn't grow up in Camelot, instead she grows up in slavery, the property of Morgause and Modred.--Lin's aunt and her half-brother. The books so far are The Firebrand and The Recruit.