Four entries with the name White Castle.
White Castle
The location of a tournament in which Perceval, Gawain, and Meliant of Lis all displayed prowess.
Source
Didot-Perceval | c. 1220-1230
White Castle
Blanc Castel
The stronghold ruled by Bliant and his brother Celinant – the two knights kept Lancelot here for a time at their castle, nursing him during a fit of madness.
Do not confuse Castle Blanc with the Castle of Bliant. In earlier versions they might have been the same, but in Malory they are different. Castle Blank might or might not have been near Listeneise (Listenois). “Blank” in Malorian names almost certainly means “white,” from the French blanc.
Sources
Vulgate Lancelot | 1215-1230
Post-Vulgate Suite du Merlin | 1230-1240
Le Morte Darthur | Sir Thomas Malory, 1469-1470
White Castle
Blanc Castel
A castle on the border of Gorre that appears several times in the Vulgate Cycle.
The Lord of the White Castle was one of the knights who opposed the Saxon invasions at the beginning of Arthur’s reign. The Lady of the White Castle is named as the cousin of Galescalain (Galeshin). Another Lord of the White Castle is called Gallides, who was defeated by Bors.
Sources
Vulgate Lancelot | 1215-1230
Vulgate Merlin | 1220-1235
White Castle
A castle in Brittany visited by Arthur after he killed the Giant of Mont St. Michel.
Source
Alliterative Morte Arthure | c. 1400
See also
Castle Blank | The Legend of King Arthur