Mahmud II (Ottoman Turkish: محمود ثانى Mahmud-u sānī, محمود عدلى Mahmud-u Âdlî; Turkish: II. Mahmud) was the 30th Sultan of the Ottoman Empire from 1808 until his death in 1839. He was born in the Topkapı Palace, Constantinople, the posthumous son of Sultan Abdul Hamid I.
His reign is recognized for the extensive administrative, military, and fiscal reforms he instituted, which culminated into the Decree of Tanzimat ("Reorganization") that was carried out by his sons Abdülmecid I and Abdülaziz I. Often known as "Peter the Great of Turkey", Mahmud's reforms included the 1826 abolishment of the conservative Janissary corps, which removed a major obstacle to his and his successors reforms in the Empire.