Köse Mihal (13th century – c. 1340); (English: Michael the beardless, and Michael with the goatee)  accompanied Osman al-Ghazi in his ascent to power as an Emir and founder of the Ottoman Empire. He is considered to be the first significant Byzantine renegade and convert to Islam to enter Ottoman service.
According to the historians Köse Mihal was the Byzantine governor of Chirmenkia (Harmankaya, today Harmanköy) and of Greek origin; his original name was "Michael Cosses". The Byzantine castle named Harmankaya is in the foothills of the Uludağ Mountains in Bilecik Turkey. It is also called Belekoma Castle. He also gained control of Lefke, Meceke and Akhisar. 
Even before his conversion to Islam, he had an amicable relationship with "The Friend of the Faithful" Osman Ghazi. He participated as an ally of Osman and his people in war, supported him as leader of and intermediary for the local Greek population, and acted as a consultant and diplomatic agent. The sources concerning the cause of his change of faith are contradictory. Firstly, that he was influenced for the sake of his friendship with Osman Ghazi, or secondly, because he had a significant dream which convinced him to become a Muslim. The time frame for his conversion are the years between 1304 and 1313. As a Muslim he was known as Köse Mihal 'Abd Allah (Abdullah). 
Up to the conquest of Bursa in 1326 Köse Mihal played an important role as a diplomatic advisor and envoy of Orhan I, the son and successor of Osman Ghazi. Köse Mihal was the first important Christian renegade, and played a significant role in the creation of the Ottoman state.  Köse Mihal's descendants, known as the Mihaloğlu were famous, particularly in the 15th and 16th centuries. They were politically and militarily successful Ottoman dignitaries and military leaders in Rumelia. However, they did not reach the very highest public offices.
After the taking of Bursa, Köse Mihal is no longer mentioned in the sources. Kreutel notes that Köse Mihal died around 1340.
According to some historians Köse Mihal was buried at Türbe, Edirne (Adrianople), in a mosque he himself built According to this tradition Köse Mihal lived until after the Ottoman capture of Adrianople by Murad I in the year 1361, and thus lived to a very great age indeed. However, Franz Babinger made a mistake. He confused Köse Mihal with Ghazi Mihal Bey, a grandson of Köse Mihal, whose Mosque complex with Imaret (destroyed) and Hamam (in ruins) is in Edirne and was completed in 1422. In the adjoining cemetery is the tomb of the founder of Türbe, Ghazi Mihal Bey.
- Dervish Ahmet-i 'Aşıki (called' Aşık Paşa, son): tevarihMenakıb u-i 'Al-i' Osman(Denkwürdigkeiten and times of the House of Osman). In Kreutel Richard Franz (Hrsg. / Editor):From Sheperd's Tent to Sublime Porte. Ottoman historian Vol 3, Graz 1959
- Joseph Hammer Purgstall:History of the Ottoman Empire. Bd.1, Pest 1827
- Nicolae Jorga:The history of the Ottoman Empire,according to sources presented verbatim reissue, Primus Verlag Darmstadt 1997
- John Leunclavius:Annales Svltanorvm Othmanidarvm, A Tvrcis Sva Lingva ScriptiFrankfurt a. M. 1588/1596, German:neuw Chronica Türckischer nation of self-described Türcke ... Frankfurt a. M. 1590
- Majoros Ferenc u. Bernd Rill:The Ottoman Empire 1300-1922, Wiesbaden 2004
- Mihaloğlu Mehmet Paşa Nüzhet: 'Ahval al-i-i Gazi Mihal ". 1897 (Ottoman)
- Mehmet Neşrî:Kitab-i Cihan-Nümâ. Partially edited and translated inJournal of the German Oriental Society. 13. Volume 1859
References and notes
- Joseph Hammer Purgstall:History of the Ottoman Empire. Erster Band, Pest 1827, p. 48
- The Last Great Muslim Empires By H. J. Kissling, Bertold Spuler, F. R. C. Bagley, pg.3
- American studies in altaic linguistics By Denis Sinor, pg.5
- Majoros Ferenc u. Bernd Rill:The Ottoman Empire 1300-1922, Wiesbaden 2004, p. 96
- Nicolae Jorga after Leunclavius (Lewenklaw) :Annales sultanorum othmanidarum, Frankfurt 1596, Sp 129
- pdf İbrahim Kaya - Şahin:AŞIKPAŞA-zade AS Historian: A STUDY ON THE TEVARiH AL-i-iOSMAN. P. 14
- Dervish Ahmet-i 'Aşıki (called' Aşık Paşa, son):Menakıb u tevarih-i 'Al-i' Osman(Denkwürdigkeiten and times of the House Osman). In Kreutel Richard Franz (Hrsg. / Editor):From Shepherd Tent to Sublime Porte. Ottoman historian Vol 3, Graz 1959, p. 32ff
- İbrahim Kaya - Şahin: AŞIKPAŞAAS-zade Historian: A STUDY ON THE TEVARiH AL-i-iOSMAN. P. 125
- Leunclavius:Annales sultanorum othmanidarum, Frankfurt 1596, Sp 129
- Mehmed Nesrî: Kitab-i Cihan-Nümâ- Nesrî Tarihi 1.Cilt, Ed: Prof. Dr. Mehmet A. Köymen and Faik Resit UNAT
- İsmail Hakkı Uzunçarşılı:Osmanli Tarihi Cilt I-IV Ankara1972 - 1978
- Franz Babinger:Mikhalik-OGHLU. In E. J. Brill's first encyclopaedia of Islam. Leiden 1913 - 1936, S.493-495
- Mehmed Neşrî, quoted inJournal of the German Oriental Society '. 13. Volume 1859, p. 214
- Nicolae Jorga:The history of the Ottoman Empire,presented by source, unchanged reissue, Primus Verlag Darmstadt 1997, Vol 2, p. 204
- Hans Joachim Kissling:Dissertationes orientales et Balcanica collectae, III. The Ottomans and Europe. Munich 1991, p. 217-225
- Richard F. Kreutel:life and deeds of the Turkish emperor. The anonymous vulgärgriechische Chronik Codex Barberinianus Graecus 111 (Anonymus Zoras). Graz et altera 1971, p. 94f
- Dervish Ahmet-i 'Aşıki (called' Aşık Paşa, son):Menakıb u tevarih-i 'Al-i' Osman(Denkwürdigkeiten and times of House Osman). In Kreutel Richard Franz (Hrsg. / Editor):From Shepherd Tent to Sublime Porte. Ottoman historian Vol 3, Graz 1959, p. 299
- Gazi Mihal Bey Camii (images, text, Turkish) queried on 8 September 2008