Mohamed I
Mehmed I Çelebi (nicknamed Kirisci, "the Executioner") (died May 26, 1421) was a sultan of the Ottoman Empire. He was one of the sons of Beyazid I.
When Timur Lenk defeated the Ottomans in the Battle of Ankara and captured Beyazid, a civil war broke out in the empire, called the Ottoman Interregnum. Mehmed gained some lands in Anatolia, which at the time gave him access to the largest source of manpower in the Ottoman lands. Mehmed supported his brother Musa in the overthrow and murder of their eldest sibling, Suleiman of Rumelia in 1410. When Musa's harsh and arbitrary rule made enemies at home as well as abroad, Mehmed made an alliance with the Byzantine Emperor Manuel II Palaeologus. With access to the Dardanelles, Mehmed quickly overran Thrace and had Musa killed.
When Mehmed stood as victor in 1413 he crowned himself as sultan in Adrianople (Edirne). He restored the empire, moved the capitol from Bursa to Adrianople and conquered parts of Albania, the Turkish emirate Candaroglu and the Christian Kingdom of Cilicia. However, as part of the alliance, Mehmed recognized the Byzantine Emperor as his "father and overlord" and remained loyal to this anomaly — which must count as the last diplomatic triumph of the Eastern Roman Empire.
Mehmed died in 1421.
The Osmanli Dynasty ruled the Ottoman Empire from 1281 to 1923, beginning with Osman I (not counting his father, Ertuğrul), though the dynasty was not proclaimed until 1383 when Murad I declared himself sultan. Before that the tribe/dynasty might have been known as Söğüt but was renamed Osmanli in honour of Osman.
The sultan was the sole regent and government of the empire, at least officially. The sultan enjoyed many titles such as Sovereign of the House of Osman, Sultan of Sultans, Khan of Khans, Commander of the Faithful and Successor of the Prophet of the Lord of the Universe. Note that the first rulers never called themselves sultans, but rather beys. See the article on state organisation of the Ottoman Empire for further information on the sultan and the structure of power.
Hereditiary heads of the House of Osman since 1926:
When Mehmed II (the Conquerer) took over Constantinople on May 29, 1453, he committed a coup d'état by replacing the
Emperor of the Roman empire (a.k.a. the Eastern Roman Empire a.k.a. Byzantine Empire) with himself. He took the title Emperor (imparator)and protector of Orthodox Christianity.
He let himself be crowned Emperor by the Patriarch of Constantinople Gennadius Scholarius, whom he protected and whose stature he elevated into leader of all the Eastern Orthodox Christians.
So in addition to being Sultan of the Muslim citisens and Khan of the Turks, he was now also styled Emperor of the Romans.
As emperor of the Romans he laid claim to all the Roman territories and succesfully managed to put most of the Roman territories (except Rome and Italy) under his own control.
