Flavius Tiberius Constantinus Augustus or Tiberius II Constantine (c. 540 - August 14, 582) was the Byzantine emperor from 574 to 582. He was a friend of Justin II, under whom he was appointed Count of the Excubitors. He took control of the empire when Justin II went insane in 574, and, in order to increase his popularity, he immediately began spending money that Justin had reserved in his treasury. While Justin was still alive, Tiberius' general Maurice fought and defeated the Persians in Armenia. When Tiberius became full emperor upon Justin's death in 578, he extended his military activities into the remnants of the Western Empire, where he made peace with the Visigoths in Spain and defeated the Moors in North Africa. Meanwhile, the Slavs began to migrate into the Balkans in 579; unfortunately, Tiberius needed the army to defend against Persian invasions, and was unable to stop the Slavic migrations.

In 582, Tiberius fell ill, and Maurice was named his heir. Maurice became emperor when Tiberius died in August.