Romeo and Juliet is a tragedy written early in the career of William Shakespeare about two young star-crossed lovers whose deaths ultimately reconcile their feuding families. It was among Shakespeare's most popular plays during his lifetime and, along with Hamlet, is one of his most frequently performed plays. Today, the title characters are regarded as archetypal young lovers.

Romeo and Juliet belongs to a tradition of tragic romances stretching back to antiquity. Its plot is based on an Italian tale, translated into verse as The Tragical History of Romeus and Juliet by Arthur Brooke in 1562 and retold in prose in Palace of Pleasure by William Painter in 1567. Shakespeare borrowed heavily from both but, to expand the plot, developed supporting characters, particularly Mercutio and Paris. Believed to have been written between 1591 and 1595, the play was first published in a quarto version in 1597. This text was of poor quality, and later editions corrected it, bringing it more in line with Shakespeare's original.

Shakespeare's use of his poetic dramatic structure, especially effects such as switching between comedy and tragedy to heighten tension, his expansion of minor characters, and his use of sub-plots to embellish the story, has been praised as an early sign of his dramatic skill. The play ascribes different poetic forms to different characters, sometimes changing the form as the character develops. Romeo, for example, grows more adept at the sonnet over the course of the play.

Romeo and Juliet has been adapted numerous times for stage, film, musical and opera. During the English Restoration, it was revived and heavily revised by William Davenant. David Garrick's 18th-century version also modified several scenes, removing material then considered indecent, and Georg Benda's operatic adaptation omitted much of the action and added a happy ending. Performances in the 19th century, including Charlotte Cushman's, restored the original text, and focused on greater realism. John Gielgud's 1935 version kept very close to Shakespeare's text, and used Elizabethan costumes and staging to enhance the drama. In the 20th century the play has been adapted in versions as diverse as George Cukor's comparatively faithful 1936 production, Franco Zeffirelli's 1968 version, Baz Luhrmann's 1996 MTV-inspired Romeo + Juliet and Carlo Carlei's 2013 version.