The Armenian Genocide (Armenian: Հայոց Ցեղասպանություն Hayots Tseghaspanutyun), also known as the Armenian Holocaust, the Armenian Massacres and, traditionally by Armenians, as Medz Yeghern (Armenian: Մեծ Եղեռն, "Great Crime") was the Ottoman government's systematic extermination of its minority Armenian subjects from their historic homeland in the territory constituting the present-day Republic of Turkey. It took place during and after World War I and was implemented in two phases: the wholesale killing of the able-bodied male population through massacre and forced labor, and the deportation of women, children, the elderly and infirm on death marches to the Syrian Desert. The total number of people killed as a result has been estimated at between 1 and 1.5 million. Other indigenous and Christian ethnic groups such as the Assyrians, the Greeks and other minority groups were similarly targeted for extermination by the Ottoman government, and their treatment is considered by many historians to be part of the same genocidal policy. It is acknowledged to have been one of the first modern genocides, as scholars point to the organized manner in which the killings were carried out to eliminate the Armenians, and it is the second most-studied case of genocide after the Holocaust. The word genocide was coined in order to describe these events.

The starting date of the genocide is conventionally held to be 24 April 1915, the day Ottoman authorities rounded up and arrested some 250 Armenian intellectuals and community leaders in Constantinople. Thereafter, the Ottoman military began expelling the Armenians from their homes throughout Turkey, forcing them onto roads that led to the Syrian desert hundreds of miles away. They were deprived of food and water and subjected to periodic robbery, rape, and massacre as they were marched along by military escorts. The majority of Armenian diaspora communities around the world came into being as a direct result of the Armenian Genocide.

Turkey, the successor state of the Ottoman Empire, denies the word genocide as an accurate description of the events. In recent years, it has faced repeated calls to accept the events as genocide. To date, 23 countries have officially recognized the events of the period as genocide, and most genocide scholars and historians accept this view.