John VII Palaeologus
He was the son of Andronicus IV Palaeologus and a Bulgarian princess. Originally he was not in line for succession because of his father's revolt against John V, but after Andronicus died, he ousted John V in 1390. Thinking of the future and afraid of losing the crown, he crowned his young son Andronicus V as co-emperor. A few months after coming to power he was deposed and John V was returned to power with help from the Turks and Venice.
In 1399, after a declaration of war from the Turks, Manuel II escaped from Constantinople to ask for military help in western Europe and left John VII as regent to defend the state. He defended the state for two years, hoping for a miracle, which seemed to occur in 1402 when the Turks were defeated by Timur at the Battle of Ankara. After this defeat the Turks sought peace and friendship with the Byzantine Empire. In exchange, John VII received almost all the Turkish-occupied coast on the European side Sea of Marmara, with a special gift: city of Thessalonica on the Aegean Sea, which was given to Manuel II after his return from Europe because the emperor had lost that city when he was previously its provincial governor. On Manuel II's return John VII returned power to him and until the end of his life in 1408 he was provincial governor of Thessalonica.
John VII's son Andronicus V died ten years before his father and the crown was inherited by the sons of Manuel II.