Leo I, Prince of Armenia
Leo I (Armenian: Լևոն Ա), also Levon I or Leon I, (unknown – Constantinople, February 14, 1140) was the fifth lord of Armenian Cilicia or “Lord of the Mountains” (1129/1130-1137).

He learned to exploit the open, yet restrained, hostilities between the Byzantine Empire and the Crusader principalities of Edessa and Antioch. Most of his successes benefited from Byzantium’s pre-occupation with the threats of Zengi (the atabeg of Mosul) from Aleppo and the lack of effective Frankish rule, especially in the Principality of Antioch.He expanded his rule over the Cilician plains and even to the Mediterranean shores. In his time, relations between the Armenians and the Franks (the Crusaders), two former allies, were not always as courteous as before: a major cause of dissension between them was the ownership of the strongholds of the southern Amanus, and on the neighboring coasts of the Gulf of Alexandretta.Leo was captured after being invited to a meeting by the Byzantine Emperor John II Comnenus, who had sworn a false promise of peace. Leo and two of his sons were taken captive and imprisoned in Constantinople where Leo died shortly after.