Leo IV the Khazar (Greek: Λέων ὁ Χάζαρος, Leōn ho Khazaros; 25 January 750 – 8 September 780) was Byzantine emperor from 775 to 780 AD.

[4][3][7] In 776–777, Khan Telerig of Bulgaria sought refuge in Constantinople, was baptized in the presence of Leo and married a relation of the empress consort Irene of Athens.

This demonstrates close relations between the Byzantine Empire and the Bulgars during Leo's reign, which were facilitated by his father Constantine V's successful campaigns against them between 760 and 775, establishing a state of peace.

[8] Leo continued with his father's resettlement policies, relocating prisoners from cities on the Arab border (Germanikeia, Melitene and Theodosioupolis) to newly-constructed military encampments or fortresses (castra) in Thrace.

[11] Lachanodrakon besieged Germanikeia for a time, then lifted the siege (according to Theophanes the Confessor, he was bribed to do so) and began to raid the surrounding countryside, deporting many Jacobite Christians to Thrace.