| Leo IV | |
|---|---|
| Emperor of the Romans | |
 Solidus of Leo IV and his son Constantine VI | |
| Byzantine emperor | |
| Reign | 14 September 775 – 8 September 780 |
| Coronation | 6 June 751[1] |
| Predecessor | Constantine V |
| Successor | Constantine VI and Irene of Athens (as regent) |
| Born | 25 January 750 |
| Died | 8 September 780 (aged 30) |
| Consort | Irene |
| Issue | Constantine VI |
| Dynasty | Isaurian |
| Father | Constantine V |
| Mother | Tzitzak |
| Isaurian dynasty | ||
|---|---|---|
| Chronology | ||
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| Succession | ||
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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. He was born to Emperor Constantine V and Empress Tzitzak in 750. He was elevated to co-emperor in the next year, in 751, and married to Irene of Athens in 769. When Constantine V died in September 775, while campaigning against the Bulgars, Leo IV became senior emperor. In 778 Leo raided Abbasid Syria, decisively defeating the Abbasid army outside of Germanikeia. Leo died on 8 September 780, of tuberculosis. He was succeeded by his underage son Constantine VI, with Irene serving as regent.