Caesar and Cleopatra (Shavian: ·𐑕𐑰𐑟𐑩𐑮 𐑨𐑯𐑛 ·𐑒𐑤𐑰𐑩𐑫𐑐𐑨𐑑𐑮𐑩) is a play written in 1898 by George Bernard Shaw that depicts a fictionalised account of the relationship between Julius Caesar and Cleopatra. It was first published with Captain Brassbound's Conversion and The Devil's Disciple in Shaw's 1901 collection Three Plays for Puritans. Shaw based his plot on Theodor Mommsen's The History of Rome, which presents an admiring depiction of Caesar as a strong leader and great man, contrasting his piece with Shakespeare's Antony and Cleopatra, which was based on histories by Plutarch and Holinshed. Shaw focused on the background of Roman interference in the affairs of Alexandria, which he saw as akin to the British imperialism of his day. He also portrayed Cleopatra as sixteen years old to downplay the sexual relationship between the title characters and focus on the political story.

The play was first performed in a single staged reading at Newcastle upon Tyne in March 1899, to secure the copyright, starring Mrs Patrick Campbell and Nutcombe Gould, though Shaw said that he had written the role of Caesar with Johnston Forbes-Robertson in mind. Campbell resisted Shaw's concept of her character and portrayed it more maturely. It was not staged again until March 1906, when it was played unsuccessfully in Berlin in a German translation, with cuts. Shaw's text was fully given a full staging in New York later in 1906 and in London in 1907, both starring Gertrude Elliott and Forbes-Robertson.

Numerous productions followed over the decades, and the play has been adapted for cinema, radio, television and the musical stage. The part of Caesar has been played by such actors as Alan Badel, John Gielgud, Alec Guinness, Cedric Hardwicke, Rex Harrison, Laurence Olivier, Christopher Plummer, Claude Rains and Godfrey Tearle. Cleopatras have included Peggy Ashcroft, Claire Bloom, Gwen Ffrangcon-Davies, Vivien Leigh, Lilli Palmer, Vanessa Redgrave and Dorothy Tutin.

Shaw objected to the general adulation of Shakespeare, which he dubbed "Bardolatry", and set his own Caesar and Cleopatra against Antony and Cleopatra, claiming that his characters were "real" as opposed to Shakespeare's, who were "love-obsessed". In an appraisal of Julius Caesar for The Saturday Review Shaw expressed his "revulsion of indignant contempt at this travestying of a great man as a silly braggart".

Shaw began writing the play in April 1898 and finished it by the end of the year. He based his plot on Theodor Mommsen's The History of Rome. He said, "I took the chronicle without alteration from Mommsen ... I found that Mommsen had conceived Caesar as I wished to present him". In Mommsen’s admiring depiction of Caesar as "the entire and perfect man" Shaw found the model for his hero and said that he had stuck nearly as closely to Mommsen as Shakespeare had to Plutarch or Holinshed. He misconstrued Mommsen's account of Cleopatra's age when she met Caesar: Shaw made her sixteen – five years younger than the historical Cleopatra. This suited Shaw, who was anxious to ensure that there should be no hint of a sexual liaison between the title characters.

The part of Cleopatra was written with the actress Mrs Patrick Campbell ("Stella") in mind. She and her company gave the first performance of the play while on tour, in Newcastle – a one-off performance on 15 March to secure the British copyright of the play. She did not care for the piece, and particularly for Shaw's conception of Cleopatra: her biographer Margot Peters writes that she turned "Shaw's mere kitten of a Cleopatra into an experienced pantheress". According to Peters, "She did not appreciate Shaw’s anti-romantic drama with its wise and urbane Caesar spurning the petty wiles of a very young Cleopatra and gladly turning her over to Antony". Campbell realised that the central role was Caesar, and having recently played Ophelia to Johnston Forbes-Robertson's Hamlet she did not intend to play second fiddle again. When the play was published as one of Shaw's Three Plays for Puritans he inscribed a copy for her: "To silly Stella who threw Caesar and Cleopatra into the waste paper basket, from G. Bernard Shaw".

Forbes-Robertson's performance as Hamlet in 1897 had impressed Shaw. He later said, "I wrote Caesar and Cleopatra for Forbes-Robertson, because he is the classic actor of the day, and had a right to require such a service from me. Without him Caesar and Cleopatra would not have been written".

After its one-off copyright performance, the play was not staged until 1906, when Max Reinhardt presented it in a German translation in Berlin on 31 March 1906. The production was a failure, which Shaw attributed to the heavy cuts Reinhardt made in the text, rendering the action and the characters incomprehensible to audiences.