Hacı Topal Osman Ağa also known as Osman the Lame, was a Turkish officer, a militia leader of the National Forces, a volunteer regiment commander of the Turkish army during the Turkish War of Independence who eventually rose to the rank of lieutenant colonel, and was a perpetrator of the Armenian and Pontic genocides.

The Kuva-yi Milliye were irregular Turkish militia forces active in the early period of the Turkish War of Independence. These irregular forces emerged after the occupation of the parts of Turkey by the Allied forces in accordance with the Armistice of Mudros. Later, Kuva-yi Milliye were integrated to the regular army of the Grand National Assembly. Some historians call this period (1918–20) of the Turkish War of Independence the "Kuva-yi Milliye phase".