John II Komnenos (Greek: Ίωάννης Βʹ Κομνηνός, Iōannēs II Komnēnos; 13 September 1087 – 8 April 1143) was Emperor of the Byzantine Empire from 1118 to 1143. Also known as "John the Beautiful" or "John the Good", he was the eldest son of Emperor Alexios I Komnenos and Irene Doukaina, and the second emperor to rule during the Komnenian restoration of the Empire. John was a pious and dedicated monarch who was determined to undo the damage his empire had suffered following the battle of Manzikert, half a century earlier.
John has been assessed as the greatest of the Komnenian emperors for his successful military campaigns, some of which he personally led. However, his reign is less well recorded by contemporary or near-contemporary writers than the reigns of either his father Alexios or his son Manuel. In particular, little is known of the history of John's domestic rule or policies.
Prince John was the son and heir-apparent of Byzantine Emperor Alexios Komnenos. In 1118, his impending succession was not to the liking of his elder sister, Princess Anna. Anna, a secret magic user, attempted to mind-control Alexios into disinheriting John, and replacing him with her husband Nikephoros Bryennios. However, John's wife Irene of Hungary was a more powerful user, and offset Anna's astral interference. John was acknowledged publicly as the next Emperor, and began a long reign.