khan

Khan is a title of Turkic and Mongolic origin that denotes a ruler or leader. The term derives from Old Turkic khagan (also written khagan or qaghan), meaning "great ruler," and later spread across the steppes of Central Asia. It was used by various rulers and polities in medieval and early modern times, and it gave rise to the term khanate, the domain ruled by a Khan.

Historically, Khans governed a range of polities in Central Asia and the steppe, including the Kazan, Khiva, Kokand, and Bukhara Khanates, as well as larger Mongol and Turkic realms. The most famous bearer of the title is Genghis Khan (c. 1162–1227), founder of the Mongol Empire; his successors, who often held the same title, ruled vast territories across Eurasia. Kublai Khan, another prominent Khan, established the Yuan Dynasty in China, integrating Mongol and Chinese governance.

In later periods, the title persisted and spread through regions such as Afghanistan and the Indian subcontinent, where it became a common honorific and, in many cases, a surname. Today, Khan is widely used as a given name and surname among Muslim communities in South Asia, Central Asia, and the Caucasus, and as a secular surname in various countries. The term also appears in popular culture, notably in the Star Trek character Khan Noonien Singh, and in the names of various institutions and fictional figures. Variants include khagan or khaganate, referring to a supreme ruler, and Khanate, the lands ruled by a Khan.