Leo III the Isaurian was Byzantine Emperor from 717 until his death in 741 and founder of the Isaurian dynasty. He put an end to the Twenty Years' Anarchy, a period of great instability in the Byzantine Empire between 695 and 717, marked by the rapid succession of several emperors to the throne. He also successfully defended the Empire against the invading Umayyads and forbade the veneration of icons.