Three entries with the name Alexander.
Alexander
Emperor of Greece and Constantinople, husband of Tantalis and thus the father of Alis and Alexander of Greece.
He allowed his son Alexander to travel to Britain to earn renown at the court of Arthur. When he died, his sons jointly succeeded him to the throne after some fraternal strife.
Sources
Cligés | Chrétien de Troyes, late 12th century
Parzival | Wolfram von Eschenbach, 1200-1210
Alexander
A knight captured and imprisoned, along with his brother Floris, by Eskilabon of Belamunt. He was rescued by his uncle, Gilan, and Arthur’s Sir Garel. In reward, he fought alongside Garel in a war against King Ekunaver of Kanadic.
His father was Duke Retan of Pergalt.
Source
Garel von dem blühenden Tal | Der Pleier, 1240-1270
Alexander
In the Irish tale, Eachtra an Mhadra Mhaoil, Alexander is the son of the King of India who was changed, along with his brothers, into a variety of canine creatures by his stepmother. Alexander himself was turned into a creature known as the Crop-Eared Dog.