Gündüz Alp

Gündüz Alp was the likely father of Ertuğrul (13th century) and grandfather of Osman I, the founder of the Ottoman Dynasty according to legend. had asserted that Suleyman Shah was the father of Ertuğrul. Historian Halil İnalcık argued that the latter have confused Suleyman Shah with the grandfather of Gündüz Alp, namely Mir Süleymân Alp. Three coins which read "Osman bin Ertuğrul bin Gündüz Alp" supports the view that Gündüz was Ertuğrul's father.

Family tree in Yazıcıoğlu Ali's :

Family tree in Enverî's Düstûrnâme-i Enverî:

tree chart|boxstyle=background:LightCyan;| | | Süleymân | Süleymân=Mir Süleymân Alp

Family tree in Âşıkpaşazâde's History of Âşıkpaşazâde:

Âşıkpaşazâde, in chapter fourteenth of The History of Âşıkpaşazâde, argues that Osman I put forward that he had descended from Gökalp and "Suleiman ibn Qutulmish" the founder of Anatolian Seljuk Sultanate instead of "Süleyman Şah ibn Kaya Alp". According to Erhan Afyoncu, the identity of Süleyman Şah in the Tomb of Suleyman Shah is unidentified. He also defends that the father of Ertuğrul according to the recent investigations is Gündüz Alp.

Father of Ertuğrul Three coins minted by Osman I in Yenişehir-Bursa during his reign which reads "Osman bin Ertuğrul bin Gündüz Alp" showed that the name of the father of Ertuğrul was Gündüz. Yılmaz Öztuna and demonstrated that those history books written more than six hundred years ago had erred in determining the father of Ertuğrul for some reasons, and had given Ertuğrul's father name incorrectly as Suleyman Shah instead of Gündüz Alp because of the similarity of the name of Kutalmışoğlu Suleyman Shah the founder of Seljuks of Rum, and Osman I's presumed ancestor Suleyman Shah.

Son of Ertuğrul According to Hasan bin Mahmûd el-Bayâtî'''s Câm-ı Cem-Âyîn, and a daughter named Efendize, who married her cousin Orhan. Some other sources also indicate that he had another son, Aktimur Bey who was a soldier and government official in the establishment of the Ottoman Empire. This Gündüz had another brother named Saru-Yatı (Savcı Beg). Osman I may also have had a nephew named Gündüz.

In fiction Gündüz Bey, son of Ertuğrul Bey, is a character in the Turkish TV series Diriliş: Ertuğrul and Kuruluş: Osman''.