The King and I is a stage musical, the fifth by the team of Richard Rodgers and Oscar Hammerstein II. The work is based on the 1944 novel Anna and the King of Siam by Margaret Landon and derives from the memoirs of Anna Leonowens, who became governess to the children of King Mongkut of Siam in the early 1860s. The story deals with the experiences of the British schoolteacher, who is hired as part of the King's drive to modernize his country. The relationship between the King and Anna is marked by conflict through much of the play, as well as by a love that neither is able to express. The musical premiered on March 29, 1951 at Broadway's St. James Theatre, closed on March 20, 1954 and has received tours and revivals.

In 1950, theatrical attorney Fanny Holtzmann was looking for a part for her client, veteran leading lady Gertrude Lawrence. Holtzmann realized that Landon's book would be an ideal vehicle and contacted Rodgers and Hammerstein, who were initially reluctant, but who agreed to write the musical. The pair initially sought Rex Harrison to play the supporting part of the King—he had played the role in the 1946 movie made from Landon's book—but Harrison was unavailable. They settled on Russian-American actor Yul Brynner.

Yul Brynner (Russian: Юлий Борисович Бринер, Yuliy Borisovich Bryner; July 11, 1920  – October 10, 1985) was a Russian-born stage and film actor. He was best known for his portrayal of Mongkut, king of Siam, in the Rodgers and Hammerstein musical The King and I, for which he won an Academy Award for Best Actor for the film version; he also played the role more than 4,500 times onstage. He is also remembered as Rameses II in the 1956 Cecil B. DeMille blockbuster The Ten Commandments, General Bounine in Anastasia and Chris Adams in The Magnificent Seven. Brynner was noted for his distinctive voice and for his shaven head, which he maintained as a personal trademark long after adopting it for his initial role in The King and I. He was also a photographer and the author of two books.

Yul Brynner was born Yuliy Borisovich Bryner in 1920. He exaggerated his background and early life for the press, claiming that he was born Taidje Khan of part-Mongol-Tatar parentage, on the Russian island of Sakhalin. In reality, he was born at home in a four-storey residence at 15 Aleutskaya Street, Vladivostok, in the Far Eastern Republic (present-day Primorsky Krai, Russia). He also occasionally referred to himself as Julius Briner,Jules Bryner, or Youl Bryner. A biography written by his son, Rock Brynner, in 1989 clarified these issues.