Alexios Komnenos was a Byzantine aristocrat and courtier. A son of Andronikos Komnenos and nephew of Emperor Manuel I Komnenos, he rose to the high rank of prōtostratōr in 1167. In 1176 he participated in the Myriokephalon campaign where, following the death of his older brother John, he was raised to the titles of prōtosebastos and prōtovestiarios. Following Manuel's death in 1180, he won the favour, and reportedly became the lover, of Empress-dowager Maria of Antioch. Through her he ruled the Byzantine Empire for two years as de facto regent of the underage emperor Alexios II Komnenos. The aristocracy challenged his dominance, led by the princess Maria Komnene, who plotted to assassinate the prōtosebastos. The plot was discovered and most conspirators arrested, but Maria and her husband fled to the Hagia Sophia, protected by Patriarch Theodosios Borradiotes and the common people of Constantinople.

The House of Komnenos, Latinized as Comnenus, was a Byzantine Greek noble family who ruled the Byzantine Empire in the 11th and 12th centuries. The first reigning member, Isaac I Komnenos, ruled from 1057 to 1059. The family returned to power under Alexios I Komnenos in 1081 who established their rule for the following 104 years until it ended with Andronikos I Komnenos in 1185. In the 13th century, they founded and ruled the Empire of Trebizond, a Byzantine rump state from 1204 to 1461. At that time, they were commonly referred to as Grand Komnenoi, a style that was officially adopted and used by George Komnenos and his successors. Through intermarriages with other noble families, notably the Doukas, Angelos, and Palaiologos, the Komnenos name appears among most of the major noble houses of the late Byzantine world.