John II Komnenos
All the Babenberg dukes from Leopold V onward were descended from Byzantine emperors — Leopold's mother, Theodora Komnene, being a granddaughter of the Emperor, John II Komnenos. Subsequently, Leopold V's younger son, Leopold VI, also married a Byzantine princess (Theodora Angelina), as did his youngest son (by Theodora), Frederick II, who married "Sophia Laskarina".