Murad I
Murad I (1319 (or 1326) – 1389; nick-named Hüdavendiğar, the God-like one) was the ruler of the Ottoman Empire from 1359 to 1389. He was the son of Orhan I and the Byzantine princess Helen (Nilofer) and became the ruler following his father's death in 1389. He established the Empire by building up a society and government in the newly conquered city of Adrianople (Edirne in Turkish) and by expanding the realm in Europe, bringing most of the Balkan under Ottoman rule and forcing the Byzantine emperor to pay him tribute. It was Murad who established the former Osmanli tribe into an empire. He established the title of sultan in 1383 and the corps of the Janissaries and the devşirm recruiting system. He also organised the government of the Divan, the system of timars and timar-holders (timariots) and the military judge, the kaziasker. He also established the two provinces of Anadolu (Anatolia) and Rumili (Europe).
Murad fought against the powerful emirate of Karamanid in Anatolia and against the Serbs, Bulgarians and Hungarians in Europe. His moves in the Balkans brought together a Christian coalition under the king of Hungary, but they were defeated at the Battle of Maritsa on September 26, 1371 by Murad's capable second lieutenant Lalaşahin, the first governor (Beylerbey) of Rumili. In 1366 the Serbian king was forced to pay tribute to the Sultan and in 1385 Sofia fell to the Ottomans. Murad was assassinated by Miloš Kobilic, a Serbian noble, during the Battle of Kosovo. See the conquests of Murad I.
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.
