Osman Ghazi ben Ertuğrul (
Osman Ghazi; or
Osman Bey or
Osman Alp); (1258–1326), sometimes transliterated in the past as
Othman or
Ottoman or
Atman (from the contemporary Byzantine Greek version of his name, Άτμαν) and nicknamed "Kara" ( "dark" in Turkish), was the leader of the
Ottoman Turks and the founder and namesake of
the dynasty that established and ruled the
Ottoman Empire. The state, while only a small
principality (
beylik) during Osman's lifetime, would prevail as a world empire under Osman's dynasty for the next six centuries after his death. It existed until the
abolition of the sultanate in 1922, or alternatively the proclamation of the
Republic of Turkey in 1923, or the abolition of the
caliphate in 1924.