Sheikh Mustafa Gaibi or Gaibija was a 17th-century dervish from Ottoman Bosnia whose mausoleum (turbe) at Stara Gradiška in Slavonia, in present-day Croatia, became a prominent site of ritual visitation by Muslims. He was regarded as a prophet by some Catholics. He wrote in Ottoman Turkish a discourse on the rules of the Jelveti Sufi order, to which he belonged. He also wrote letters in which he criticized various kinds of wrongdoing that he regarded as widespread in the Ottoman Empire. His letters contain mystical-looking expressions that are difficult to understand. He is reputed to have predicted the defeat of Ottomans at the Battle of Vienna in 1683 and the subsequent loss of their territories north of the river Sava. According to a local Catholic source, an Ottoman soldier killed Gaib