Byzantine emperor (1195-1203). Alexios was born around 1153, the elder brother of Isaac II, first ruler of the Angelos dynasty, whom he deposed on 8 April 1195 and subsequently had blinded and imprisoned.
Generally ranked among the most incompetent Byzantine sovereigns, Alexios III oppressed his people through extravagance and heavy taxes, among them a “German tax” (Gr. alamanikon) in 1197, reputedly required to ward off the German emperor Henry VI’s crusading plans against Byzantium. Several Greek and Balkan local rulers rebelled against Alexios, among them Leo Sgouros and Manuel Kammytzes, who proclaimed their independence in the northeastern Peloponnese and northern Thessaly, while Alexios almost lost his throne in a court coup led by John Axouchos Komnenos Pachys (1200/1201).
In the summer of 1203 the Fourth Crusade arrived before the walls of Constantinople, and on 17/18 July Alexios ignominiously fled from his capital with the imperial treasury and crown jewels, escaping to Mosynopolis in Thrace, while the crusaders installed Isaac II and the latter’s son Alexios IV as co-emperors. In the summer of 1204, Alexios III allied himself with Alexios V Doukas Mourtzouphlos, who had overthrown the co-emperors (January 1204), but fled again after the second capture of Constantinople by the crusaders (12-13 April). Alexios III gave his daughter Eudokia Angelina to Mourtzouphlos in marriage, but aspired to regain the throne for himself; in August 1204 he had Mourt- zouphlos blinded, and Eudokia was married to the nobleman Leo Sgouros, whose power was still in the ascendant. Soon afterward Alexios III and his wife Euphrosyne Doukaina were captured by Boniface of Montferrat (late 1204) and detained in Thessaly. Ransomed in 1209/1210 by his relative Michael I of Epiros, Alexios was sent to the Saljûq sultan of Rûm, Kay-Khusraw I, with whose help he hoped to regain his crown. However, after the defeat of the Saljûqs by Theodore I Laskaris in spring 1211, Alexios was seized and incarcerated in the Hyakinthos monastery in Nicaea, where he died soon after.