Leo IV the Khazar, Byzantine emperor (died 780)

Leo IV the Khazar 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.

January 25 is the 25th day of the year in the Gregorian calendar; 340 days remain until the end of the year.