Leading British ballet company and school, based at the Royal Opera House, Covent Garden, London. Until 1956 it was known as the Sadler's Wells Ballet. It was founded 1931 by Ninette de Valois, who established her school and company at the Sadler's Wells Theatre. It moved to Covent Garden 1946. Frederick Ashton became principal choreographer 1935, providing the company with its uniquely English ballet style. Leading dancers included Margot Fonteyn, Rudolf Nureyev, Alicia Markova, and Antoinette Sibley.

The company's roots can be traced to the invitation by Lilian Baylis to Ninette de Valois to establish her school and company at the rebuilt Sadler's Wells Theatre 1931. The Vic-Wells Ballet, as it was then known, developed its popularity largely through the performances of Alicia Markova and through de Valois' shrewd artistic policies and organizational prowess. In 1946, the company changed its name to Sadler's Wells Ballet and shifted base from the Wells Theatre to the Royal Opera House, Covent Garden. The same year saw the founding of a second, touring troupe, the Sadler's Wells Opera Ballet (later Theatre Ballet). The touring company again changed its name 1976 to Sadler's Wells Royal Ballet. In 1963 de Valois resigned in favour of Frederick Ashton as director. He was responsible for creating such ballets as Marguerite and Armand for Margot Fonteyn, whose partnership with Rudolf Nureyev ushered in the Royal Ballet's golden age. Kenneth MacMillan took over from Ashton 1970 and strengthened both companies' modern-ballet styles with works from US choreographers such as Jerome Robbins and Glen Tetley. Anthony Dowell took over from Norman Morrice 1986 and declared a policy of rejuvenating the classics, as in his Swan Lake 1987, which he recreated the nearest approximation to the original 1895 choreography. He also commissioned new works such as MacMillan's The Prince of the Pagodas 1989.

Russian ballet company founded 1776 and based at the Bolshoi Theatre in Moscow. With their mixed repertory of classics and new works, the Bolshoi is noted for its grand scale productions and the dancers' dramatic and eloquent technique. From 1964 its artistic director has been the choreographer Yuri Grigorovich (1927- ).

The Bolshoi was formed by English entrepreneur Michael Maddox and Prince Urusov, a patron of the arts. Its dancers were recruited from the Moscow Orphanage where the first classes were conducted 1773. It provided dancers for the Petrovsky Theatre, established 1780, on the site of the present Bolshoi Theatre, which was opened 1825. In contrast to the Kirov Ballet where the dancing was more purist, the Bolshoi tended to be earthier and more contemporary in style and theme. Initially overshadowed by the Kirov, the Bolshoi came into its own in the late 19th century with the first staging of Petipa's Don Quixote 1877 and Swan Lake 1877. Under Alexander Gorsky (died 1942), the Bolshoi's style of highly dramatic action woven into the dance, innovative stage designs, and symphonic music, was developed. It was not until Leonid Lavrovsky (1905-1967) transferred as artistic director from the Kirov to the Bolshoi 1944, along with prima ballerinas Galina Ulanova and Maya Plisetskaya that the creative emphasis shifted to Moscow. Since the 1960s the Bolshoi has concentrated on highly spectacular and heroic productions of the classics and modern works, such as Spartacus 1968 and The Golden Age 1982. 

Russian ballet company based in St Petersburg, founded 1738. Originally called the Imperial Ballet, it was renamed 1935 (after an assassinated Communist Party leader). The Kirov dancers are renowned for their cool purity of line, lyrical mobility, and gravity-defying jumps; the corps de ballet is famed for its precision and musicality. The classical ballets of Marius Petipa make up the backbone of the company's repertory and many of the world's most acclaimed classical dancers, such as Anna Pavlova, Rudolf Nureyev, and Mikhail Baryshnikov, are graduates of the company. Oleg Vinogradov (1937- ) has been its artistic director since 1972.

Formed 1738 as the St Petersburg School of Ballet by French dancing master, Jean-Baptiste Landé, and Empress Anna Ivanovna, the company performed for the court during the mid-18th century. With the influx of French and Italian teachers, virtuoso dancers, and choreographers during the 19th century, the company grew in strength. It was under the directorship of Marius Petipa that the company was given a permanent home at the Maryinsky Theatre 1860 (still the Kirov's base). Petipa's ballets of the 1890s, The Sleeping Beauty 1890, Raymonda 1898, La Bayadère 1877, and Swan Lake 1895 form the bedrock of the classical, in particular the Kirov's, repertory. After the 1917 revolution, the company was renamed the Maryinsky State Theatre and an attempt was made to bring dance within the reach of the people rather than as a diversion for the aristocracy. During the 1920s and 1930s, the company, called the State Academy Theatre for Opera and Ballet (GATOB), created some of the most important Soviet ballets, culminating in Romeo and Juliet 1940.

After World War II, the emphasis shifted from Leningrad to Moscow's Bolshoi Ballet, but the Kirov's reputation was enhanced when it first visited Paris, London, and New York 1961. It was during these visits abroad that some of the company's most acclaimed dancers defected - Rudolf Nureyev 1961, Natalia Makarova 1970, and Mikhail Baryshnikov 1974 - artists who suffered from the isolation and creative sterility that marked the company since the 1950s. In the 1990s the company continued to tour the cultural centres of the West.