This article is about the Byzantine Emperor. There is also an article on Pope Leo VI

Leo VI the Wise (September 19, 866 – May 11, 912) was Byzantine emperor from 886 to 912. He inherited from his father Basil I an empire that was much larger and stronger than it had been since the height of the Roman Empire in the 2nd century. However, he and his father hated each other; it is possible that Leo was not Basil's son at all, but the son of Michael III, the emperor before Basil. Basil had almost had Leo blinded as a teenager. In 886, Basil died in a hunting accident, though he claimed on his deathbed that there was an assassination attempt in which Leo was possibly involved.

Leo completed work on the Basilica, the Greek translation and update of the law code created by Justinian I, which had been started during the reign of Basil.

Leo was not as successful in battle as Basil had been. Basil had never lost to the Bulgarians, but in 894 they routed Leo's army. In 895 he was more successful, after first allying with the Magyars, but in 896, without Magyar help, the Byzantines were again defeated.

Leo caused a minor scandal with his numerous marriages. His first wife, whom Basil had forced him to marry, died in 897, and he re-married Zoë Zaützina, daughter of his counsellor Zaützes, though she died as well in 899. After this marriage Leo created the title of basilopator ("father of the emperor") for his father-in-law. After Zoë's death a third marriage was technically illegal, but he married again, only to have his third wife die in 901. Instead of marrying a fourth time, which would have been an even greater sin than a third marriage (according to the Patriarch Nicholas Mysticus) Leo instead took a mistress. He was allowed to marry her when she gave birth to a son in 904, but with many penalties, such as the refusal to legitimize his wife as empress.

In 907 Constantinople was attacked by the Kievan Rus', who were seeking favourable trading rights with the empire. Leo paid them off, but they attacked again in 911, and a trade treaty was finally signed. However, Leo was not as successful against the Arabs, who defeated his fleet when he attempted to take back Crete in 912. After this defeat Leo quickly became ill and died. As his son was still a child, Leo's brother and nominal (though powerless) co-emperor Alexander became full emperor.