Şehzade Ertuğrul Osman Efendi (; 18 August 1912 – 23 September 2009), also known as Osman Ertuğrul Osmanoğlu with a surname as required by the Turkish Republic, was a prince of the Ottoman Empire and the 43rd Head of the Imperial House of Osman from 1994 until his death.

Until the abolition of the monarchy on 1 November 1922, Osman was addressed as His Imperial Highness Şehzade Ertuğrul Osman Efendi Hazretleri, Imperial Prince of the Ottoman Empire. He is known in Turkey as "the last Ottoman". He was the second and youngest son of Şehzade Mehmed Burhaneddin (Yıldız Palace, 19 December 1885 – New York City, United States, 15 June 1949, and buried in Damascus). His father served as a Captain of the Ottoman Army. Ertuğrul Osman's mother was Burhaneddin's second consort, Aliye Melek Nazlıyar Hanım (Adapazarı, 13 October 1892 – Ankara, 31 August 1976), daughter of Hüseyin Bey. They married at Nişantaşı, Nişantaşı Palace, Pera (today Beyoğlu) on 7 June 1909 and divorced in 1919. Osman's paternal grandparents were Sultan Abdul Hamid II and Mezidemestan Kadın.

In 1924, while studying in Vienna, Austria, he received news that all members of the Sultan's family were to be exiled. He worked as a consultant for Canadian company Wells Overseas which often sent him to South America.

Osman lived modestly in Manhattan after 1945, residing in a two-bedroom apartment above a restaurant. He returned to Turkey in 1992, having been invited by the country's government. He became the 43rd Head of the Imperial House of Osman in 1994, after the death of Şehzade Mehmed Orhan.

Osman was granted a Turkish passport and citizenship in 2004. He spoke Turkish, English, German and French fluently and understood Italian and Spanish.

Osman died on 23 September 2009 in his sleep from kidney failure, at the age of 97. His coffin was draped with the Imperial Ottoman Standard and his funeral was attended by Turkish government ministers.

  • Ertugrul Osman – Daily Telegraph obituary