Ertuğrul (1191 / 1198 – 1281) is the father of Osman I, the founder of the Ottoman Empire.

He is the leader of the Kayi clan of the Oghuz Turks.

When arriving in Anatolia from Merv (Turkmenistan) with his four hundred horsemen to aid the Seljuks of Rum against the Byzantines, Ertugrul sets off the chain of events that will ultimately lead to the founding of the Ottoman Empire.

Like his son, Osman, and his future descendants, Ertugrul is often referred to as a Ghazi, a heroic champion fighter for the cause of Islam.