Byzantine Emperors, Theodosius I, II and III
Known as The Great, (347-395) he was the son of the Spanish general Flavius Theodosius. He was working as a military governor in Moesia when his father was executed by Valentinian in 376. After his father's death, Theodosius withdrew from military life until 379, after which emperor Valens is defeated and killed by the Visigoths at Adrianople (Edirne) in 378 and emperor Gratian named him Augustus (co-ruler) of the East. In 381, he signed for an alliance with the Visigoths to keep them under control, who had been invading areas of the Empire since 375 instead of becoming part of the Roman Army.
In 380, he issued a law ordering all citizens to believe in the Nicene Creed of the Council in 325 to be considered Catholic Christians. He severely acted against paganism like closing and even destroying temples and ending the Olympic Games. In 381 he convened the second Ecumenical Council in Istanbul (First Council of Constantinople). In 390 AD he brought the Egyptian Obelisk carved from granite from Temple of Luxor in Karnak to Istanbul and had it erected in the Hippodrome. In 391 and 392, Theodosius prohibited sacrifices and worshiping of pagan gods, making Christianity the only religion of the state. In 394, he fought his pagan enemies and won. Theodosius became ill and died in 395. He divided the Roman Empire between his two sons.
Ruled between 408-450, he was the son and successor of Arcadius. He preferred the study of theology and astronomy to public affairs leaving it to his sister Pulcheria and his wife Eudocia. The most important political events of his reign were the establishment of Valentinian III as emperor in the West in 425 and the raids into the Empire by the Huns under Attila. In 431, Theodosius summoned the Council of Ephesus, which condemned Nestorianism, and in 449 he convoked and upheld the Robber Synod, which declared the orthodoxy of Eutychianism. He also founded the Constantinople University in 425, declared the Theodosian Code (Codex Theodosianus) in 438, and restored the City Walls. Marcian, His brother-in-law, succeeded him when he died in 450 for a riding accident.
Ruled between 715-717, he was a tax collector at Adramyttium (modern Edremit in the Aegean region) and became an imperial candidate by troops revolted against Anastasius II. He entered Constantinople (Istanbul) as an Emperor in 715 after a siege of six months, deposing Anastasius. He replaced the image of the Sixth Ecumenical Synod. In 716 he signed a treaty with the Bulgarians against Arab attacks on Constantinople, establishing the border in Thrace. In 717 Leo III rebelled against Theodosius' rule and captured his son in Nicomedia (modern Kocaeli), so Theodosius chose to resign the throne. Along with his son, he subsequently entered the clergy and became bishop of Ephesus, where he's buried.