The most famous of the Turcopoles, christianized ex-Turkish mercenaries in Byzantine service during the period of the crusades.
Tatikios was chiefly active in the last two decades of the eleventh and the beginning of the twelfth centuries, mainly in the service of the Byzantine emperor Alexios I Komnenos, who rewarded him with various high offices for his services against Normans, Saljûqs of Rûm, Pechenegs, Cumans, and crusaders.
During the First Crusade (1096-1099), Tatikios played an instrumental role in the surrender of Nicaea (mod. Iznik, Turkey) by the Saljûqs to the Byzantines (June 1097) as well as in the ensuing Byzantine-crusader negotiations. In early 1098, however, in the course of the joint Byzantine-crusader operations against Antioch (mod. Antakya, Turkey), the Norman Bohemund of Tarento succeeded in persuading Tatikios to flee to Cyprus on the grounds that his life and the lives of his soldiers were in imminent danger. Bohemund claimed that Alexios I had secretly made contact with a Muslim army coming to the relief of Antioch, and that on hearing of this the enraged crusaders would naturally seek revenge on the treasonous imperial agent. Tatikios is last heard of in Cyprus between 1099 and 1103 as periphanes tate kephale (deputy admiral) of the Byzantine navy, defeating a Pisan fleet off the shores of Rhodes (mod. Rodos, Greece) that was on its way to assist Bohemund (I), now prince of Antioch.