Dame Antoinette Sibley, DBE (born 27 February 1939) is a British prima ballerina. She joined the Royal Ballet from the Royal Ballet School in 1956 and became a soloist in 1960. She was celebrated for her partnership with Anthony Dowell. After her retirement from dancing in 1989 she became President of the Royal Academy of Dance in 1991, and guest coach at the Royal Ballet (1991) and Governor, Royal Ballet Board (2000).
Sibley was born in the London suburb of Bromley, the daughter of Edward G Sibley and his wife Winfred, née Smith. She was educated at the Arts Educational Schools and the Royal Ballet School. Her first appearance on the stage was as a swan in Swan Lake in January 1956, when still a student. In July of the same year she joined the Royal Ballet company.
Initially Sibley had small roles such as a friend of Swanhilda in Coppélia and Red Riding Hood in Sleeping Beauty. Joan Lawson in The Dancing Times wrote of Sibley's dancing, "lyrical qualities and beautifully flowing line". On 21 March 1959 Dame Ninette de Valois, artistic director of the Royal Ballet, allowed Sibley to undertake her first major role, at a matinée at the Royal Opera House. Sibley was cast as Swanhilda in Coppelia. During 1959 Sibley had the chance to be tutored by one of the greatest ballerinas of the twentieth century, Tamara Karsavina. Karsavina said to Sibley, "To get the full benefit from battements frappés we must train our muscles to give a quick reaction. This means that the dégagé must be sharp and in the nature of a 'hit out'."