Tatars (Tatar: Tatarlar/Татарлар), also Tartar, is a collective name applied to the Turkic speaking people of Eastern Europe and Central Asia. The name is derived from Tartarus, L.W. Moses, "Mongolia - Ethnography and early tribal history", Encyclopaedia Britannica, Online Edition, (LINK), the Greek god of the underworld, as a reference to the brutality of Turco-Mongol hordes in Europe. It was first used to describe the peoples that overran parts of Asia and Europe under Mongol leadership in the 13th century. It was later extended to include almost any Asian nomadic invader, whether from Mongolia or the fringes of Western Asia. Before the 1920s Russians used the name Tatar to designate numerous peoples from the Azeris to tribes of the Siberia.

Most current day Tatars live in the central and southern parts of Russia (the majority in Tatarstan), Ukraine, Poland and in Bulgaria, China, Kazakhstan, Romania, Turkey, and Uzbekistan. They collectively numbered more than 10 million in the late 20th century. Most Tatars are Sunni Muslims.

The majority—in European Russia—are descendants of Eastern European Volga Bulgars who were conquered by the Mongol invasion of the 13th century and kept the name of their conquerors. Tatars of Siberia are survivors of the once numerous Turkic-Mongolian population of the Ural-Altaic region, mixed to some extent with the speakers of Uralic languages, as well as with Mongols.