Dame Margaret Evelyn de Arias DBE (née Hookham; 18 May 1919 – 21 February 1991), known by the stage name Margot Fonteyn (/fɒnˈteɪn/), was an English ballerina. She spent her entire career as a dancer with the Royal Ballet (formerly the Sadler's Wells Theatre Company), eventually being appointed prima ballerina assoluta of the company by Queen Elizabeth II.

Beginning ballet lessons at the age of four, she studied in England and China, where her father was transferred for his work. Her training in Shanghai was with Russian expatriate dancer Georgy Goncharov, contributing to her continuing interest in Russian ballet. Returning to London at the age of 14, she was invited to join the Vic-Wells Ballet School by Ninette de Valois. She succeeded Alicia Markova as prima ballerina of the company in 1935. The Vic-Wells choreographer, Sir Frederick Ashton, wrote numerous parts for Fonteyn and her partner, Robert Helpmann, with whom she danced from the 1930s to the 1940s.

In 1946, the company, now renamed the Sadler's Wells Ballet, moved into the Royal Opera House at Covent Garden where Fonteyn's most frequent partner throughout the next decade was Michael Somes. Her performance in Tchaikovsky's The Sleeping Beauty became a distinguishing role for both Fonteyn and the company, but she was also well known for the ballets created by Ashton, including Symphonic Variations, Cinderella, Daphnis and Chloe, Ondine and Sylvia.

In 1949, she led the company in a tour of the United States and became an international celebrity. Before and after the Second World War, Fonteyn performed in televised broadcasts of ballet performances in Britain and in the early 1950s appeared on The Ed Sullivan Show, consequently increasing the popularity of dance in the United States.

In 1955, she married the Panamanian politician Roberto Arias and appeared in a live colour production of The Sleeping Beauty aired on NBC. Three years later, she and Somes danced for the BBC television adaptation of The Nutcracker. Thanks to her international acclaim and many guest artist requests, the Royal Ballet allowed Fonteyn to become a freelance dancer in 1959.

In 1961, when Fonteyn was considering retirement, Rudolf Nureyev defected from the Kirov Ballet while dancing in Paris. Fonteyn, though reluctant to partner with him because of their 19-year age difference, danced with him in his début with the Royal Ballet in Giselle on 21 February 1962. The duo immediately became an international sensation, each dancer pushing the other to their best performances. They were most noted for their classical performances in works such as Le Corsaire Pas de Deux, Les Sylphides, La Bayadère, Swan Lake, and Raymonda, in which Nureyev sometimes adapted choreographies specifically to showcase their talents. The pair premièred Ashton's Marguerite and Armand, which had been choreographed specifically for them, and were noted for their performance in the title roles of Sir Kenneth MacMillan's Romeo and Juliet.

The following year, Fonteyn's husband was shot during an assassination attempt and became a quadriplegic, requiring constant care for the remainder of his life. In 1972, Fonteyn went into semi-retirement, although she continued to dance periodically until the end of the decade. In 1979, she was fêted by the Royal Ballet and officially pronounced the prima ballerina assoluta of the company. She retired to Panama, where she spent her time writing books, raising cattle, and caring for her husband. She died from ovarian cancer exactly 29 years after her premiere with Nureyev in Giselle.

Margaret Evelyn Hookham was born on 18 May 1919 in Reigate, Surrey, to Hilda (née Acheson Fontes) and Felix John Hookham. Her father was a British mechanical engineer, who worked for the British-American Tobacco Company. Her mother was the illegitimate daughter of an Irish woman, Evelyn Acheson, and the Brazilian industrialist Antonio Gonçalves Fontes. Hookham had one sibling, her older brother Felix. The family moved to Ealing, where her mother sent her four-year-old daughter with her brother to ballet classes with Grace Bosustow. Her mother accompanied Hookham to her earliest lessons, learning the basic positions alongside her daughter in order to improve her understanding of what a ballet student needed to develop. Over the years, Hilda provided constant support, guidance and critique to her daughter; she became a well-known backstage presence at Hookham's performances, earning the nickname "Black Queen" from Hookham's teachers and colleagues. While some children might have balked at such overbearing attention from a parent, Hookham accepted her mother's help with "affectionate and unembarrassed naturalness".