The Tsar Bell, also known as the Tsarsky Kolokol, Tsar Kolokol III, or Royal Bell, is a 6.14-metre-tall (20.1 ft), 6.6-metre-diameter (22 ft) bell on display on the grounds of the Moscow Kremlin. The bell was commissioned by Empress Anna Ivanovna, niece of Peter the Great.

A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be made by an internal "clapper" or "uvula", an external hammer, or—in small bells—by a small loose sphere enclosed within the body of the bell.