In the late 13th century a fighting force of Muslim warriors (ghazis) were trying to gain some control between Mongol Empire and the Byzantine in Anatolia (modern day Turkey). They had a very little room to move until Osman led those nomads. Ottomans (Osmani) name was chosen for the rulers and the area they controlled.
After few centuries, rising to become a massive world power. The sultans of the Ottoman Empire who were all members of the Ottoman dynasty, ruled over the transcontinental empire from its perceived inception in 1299 to its dissolution in 1922. The Ottoman sultan was a very powerful ruler. He was head of his empire and all the subjects, giving him control over politics and the military.
Here is a list of all the rulers of the Ottoman Empire.