Janissaries, or Janizaries, soldiers of the elite army units of the Turkish Ottoman Empire. The corps of Janissaries originated as a regiment of Christian soldiers recruited by the sultan Orkhan (reigned 1326?–62?). His successors used Christian boys who were taken from their parents, converted to Islam, and taught fanatic loyalty to the sultan. Although legally slaves, they were used to staff the Ottoman government as well as to man the Janissary corps.

The Janissaries were trained under iron discipline and became the most feared fighters of the age. After 1600, however, conscription gradually ceased; the corps came to include native Muslims and membership was partly hereditary. The Janissaries became corrupt and overthrew sultans who tried to discipline them. The corps was abolished in 1826 after an unsuccessful revolt.