The Odjak of Algiers((efn|also spelled Ujaq was a unit of the Algerian army. It was a highly autonomous part of the Janissary Corps, acting completely independently from the rest of the corps, similar to the relationship between Algiers and the Sublime Porte. Led by an Agha, they also took part in the country's internal administration and politics, ruling the country for several years. They acted as a defense unit, a Praetorian Guard, and an instrument of repression until 1817.

A janissary was a member of the elite infantry units that formed the Ottoman Sultan's household troops. They were the first modern standing army, and perhaps the first infantry force in the world to be equipped with firearms; adopted during the reign of Murad II. The corps was established either under Sultans Orhan or Murad I, and dismantled by Mahmud II in 1826.