The Bolshoi Theatre is a historic theatre in Moscow, Russia, designed by architect Joseph Bové, which holds performances of ballet and opera. The theatre's original name was the Imperial Bolshoi Theatre of Moscow, while the St. Petersburg Bolshoi Theatre (demolished in 1886), was called the Imperial Bolshoi Kamenny Theatre.

At that time, all Russian theatres were imperial property. Moscow and St. Petersburg each had only two theatres, one intended for opera and ballet (these were known as the Bolshoi Theatres), and one for plays (tragedies and comedies). Because opera and ballet were considered nobler than drama, the opera houses were named "Grand Theatres" ("Bolshoi" is Russian for "large" or "grand") and the drama theatres were called the "Smaller Theatre" ("Maly" is Russian for "small", "lesser", or "little").

The Bolshoi Ballet and Bolshoi Opera are amongst the oldest and most renowned ballet and opera companies in the world. It is by far the world's biggest ballet company, having more than 200 dancers. The theatre is the parent company of The Bolshoi Ballet Academy, a world-famous leading school of ballet. It has a branch at the Bolshoi Theatre School in Joinville, Brazil..

The company was founded on 28 March 1776 by Prince Pyotr Vasilyevich Urusov and Michael Maddox. Initially, it held performances in a private home, but it acquired the Petrovka Theatre and on 30 December 1780 it began producing plays and operas, thus establishing what was to become the Bolshoi Theatre. With the destruction by fire of the Petrovka Theatre on 8 October 1805, it was replaced on 13 April 1808 with the opening of New Arbat Imperial Theatre, but, as a consequence of the French invasion of Moscow in 1812, fire destroyed that theatre.

The current theatre was built on Theatre Square between 1821 and 1824. It was designed by architect Andrei Mikhailov (who had also built the nearby Maly Theatre in 1824) and it opened on 18 January 1825 as the Bolshoi Petrovsky Theatre with a performance of Fernando Sor's ballet, Cendrillon. Initially, it presented only Russian works, but foreign composers entered the repertoire around 1840.

The Bolshoi has been the site of many historic premieres, including Tchaikovsky's The Voyevoda and Mazeppa; Modest Mussorgsky's one version of Boris Godunov (1888); Rachmaninoff's Aleko and Francesca da Rimini; Nikolai Rimsky-Korsakov's opera The Maid of Pskov; Dmitri Shostakovich's opera Lady Macbeth of the Mtsensk District (1935).

The main building of the theatre, rebuilt and renovated several times during its history, is a landmark of Moscow and Russia (its iconic neoclassical façade is depicted on the Russian 100-ruble banknote). On 28 October 2011, the Bolshoi was re-opened after an extensive six-year renovation. The official cost of the renovation is 21 billion rubles ($688 million). The renovation included restoring acoustics to the original quality (which had been lost during the Soviet Era), as well as restoring the original Imperial decor of the Bolshoi.