Alexios I Megas Komnenos
Alexios I Megas Komnenos (c. 1182–1222) founded the Empire of Trebizond with his brother David. A grandson of Emperor Andronikos I, he seized Trebizond in April 1204 with his aunt Queen Tamar of Georgia's support, as the Fourth Crusade took Constantinople.
While David conquered the western Pontic lands, Alexios held Trebizond against a Seljuk siege. In 1214 the Turks captured him defending Sinope; he was freed after the city surrendered on becoming the vassal of Sultan Kaykaus I.
Sinope's loss isolated Trebizond from the other Greek lands. He died on 1 February 1222, leaving the throne to his son-in-law Andronikos.