Leo IV the Khazar

Leo IV the Khazar (750–780), son of Constantine V by the Khazar princess Tzitzak, was crowned co-emperor in 751 and married Irene of Athens in 769. He succeeded his father in September 775, already suffering from tuberculosis, and his illness and the youth of his son gave his half-brothers hope of the throne.

In 776 he named his young son Constantine VI heir and pardoned his half-brothers after their failed plot. His armies defeated the caliph's forces at Germanikeia in 778 and repelled another invasion the next year. When Leo died on 8 September 780, the nine-year-old Constantine became emperor under Irene's regency.