John VIII Palaiologos

John VIII Palaiologos (Greek: Ἰωάννης Παλαιολόγος, romanized: Iōánnēs Palaiológos; 18 December 1392 – 31 October 1448) was the penultimate Roman emperor to rule in Constantinople. Ruling from 1425 to 1448, he attempted to bring about the reunification of the Orthodox and Catholic churches and prioritised the protection of Constantinople against the Ottoman Empire. He was succeeded by his brother, Constantine XI, who would become the final emperor.

Source: Wikipedia — https://en.wikipedia.org/wiki/John_VIII_Palaiologos