Ertugrul Osman (Ottoman Turkish: ?????? ??????), also known as Osman Ertugrul Osmanoglu with a surname as required by the Turkish Republic (18 August 1912 – 23 September 2009), was an Imperial Prince (or Sehzade) of the Ottoman Empire and the 43rd Head of the Imperial House of Osman from 1994 until his death.
Had the Ottoman Empire not been dissolved and succeeded by the Republic of Turkey, he would have become caliph and Grand Sultan Osman V.
He was also known as Grand Sultan Ertugrul II in reference to Ertugrul, the father of Osman I.
Until the abolition of the monarchy on 1 November 1922, Osman was addressed as His Imperial Highness Sehzade Ertugrul Osman Efendi Hazretleri, Imperial Prince of the Ottoman Empire.
He is known as "the Last Ottoman" or "the Last Ottoman Emperor" by the Turkish society.