Telerig (Bulgarian: Телериг) was the ruler of Bulgaria 768–777. He was the immediate successor of Pagan, who was murdered in 768. In May 774, the Byzantine Emperor Constantine V Kopronymos embarked on a major expedition against Bulgaria, leading his field army on land, and dispatching a fleet of 2,000 ships carrying horsemen towards the Danube delta. The fleet dismebarked in the vicinity of Varna, but the emperor inexplicably retreated.
Shortly afterwards the two sides signed a truce promising the cessation of hostilities. However, in October 774 Telerig sent an army of 12,000 men to raid Berzitia, Macedonia and to transfer its population to Bulgaria. Collecting a large army of 80,000 troops, Constantine V surprised the Bulgarians and won a resounding victory. The subsequent attack on Bulgaria failed, because the imperial fleet encountered contrary winds in the Black Sea.
At this point Telerig sent a secret emissary to Constantine V, indicating his intention to flee Bulgaria and seek refuge with the emperor, and seeking assurances of hospitality. Telerig succeeded in having the emperor betray his own agents in Bulgaria, who were duly rounded up and executed. The expected Byzantine retaliation failed to materialize as Constantine V died in 775. In spite of his apparent success, Telerig found it necessary to flee to the new Byzantine emperor, Leo IV the Khazar in 777. The Byzantine government gave Telerig asylum and the title of patrikios. Telerig converted to Christianity under the name of Theophylaktos and married a cousin of the Empress Eirene.