Abdulmejid II or Abdulmecid II was the last Ottoman caliph, the only caliph of the Republic of Turkey, and head of the Osmanoğlu family from 1926 to 1944. As opposed to previous caliphs, he used the title Halîfe-i Müslimîn, instead of Emîrü'l-Mü'minîn.

The caliphate of the Ottoman Empire was the claim of the heads of the Turkish Ottoman dynasty to be the caliphs of Islam in the late medieval and early modern era. During the period of Ottoman expansion, Ottoman rulers claimed caliphal authority after the conquest of Mamluk Egypt by sultan Selim I in 1517 and the abolition of the Mamluk-controlled Abbasid Caliphate. This left Selim as the Defender of the Holy Cities of Mecca and Medina and strengthened the Ottoman claim to leadership in the Muslim world.