Isaac Komnenos (son of Alexios I)

Isaac Komnenos
Sebastokrator of the Byzantine Empire
Mosaic of Isaac Komnenos the Porphyrogennetos from the Chora Church
Born	(1093-01-16)16 January 1093
Died	After 1152
Spouse	Irene
Issue	John Tzelepes Komnenos Anna Komnene Andronikos I Komnenos
Dynasty	Komnenoi
Father	Alexios I Komnenos
Mother	Irene Doukaina

Isaac Komnenos or Comnenus (Greek: Ἰσαάκιος Κομνηνός, Isaakios Komnēnos; 16 January 1093 – after 1152) was the third son of Byzantine Emperor Alexios I Komnenos (r. 1081–1118) and Empress Irene Doukaina. He was raised to the high rank of sebastokrator by his older brother John II Komnenos, but they later fell out and Isaac was exiled by John for several years. During the struggle for John's succession in 1143, he supported the unsuccessful candidacy of his nephew, likewise named Isaac, over the younger Manuel I Komnenos. A few years later, he was forced to retire to a monastery by Manuel. Isaac was noted for his erudition and his patronage of learning.

He was the brother of Emperor John II Komnenos and the historian Anna Komnene. Isaac was given the dignity of Caesar by his father.

During and after the succession of John II in 1118, Isaac supported his elder brother against the intrigues of Empress-dowager Irene and their sister Anna, who favoured the candidacy of Anna's husband, Nikephoros Bryennios the Younger. In return, John II raised Isaac to the elevated dignity of sebastokratōr, which marked him as a near-equal to the emperor. In contrast to his brother, who was chiefly engaged in warfare throughout his reign, Isaac was also a scholar and patron of learning. He is known to have composed and compiled poetry, and is sometimes identified with the writer called "Isaac Komnenos the porphyrogennetos" who composed three philosophical treatises based on Proclus and two commentary works on Homer.

By ca. 1130 (and possibly as early as 1122) however, John and Isaac had become estranged, and Isaac was forced to flee Constantinople with his sons for six years after an alleged conspiracy. Isaac found refuge at the court of the Danishmendid emir Gümüshtigin Ghazi II ibn Danishmend at Melitene. During this time, he also undertook a pilgrimage to the Holy Land.