King Lear is a tragedy written by William Shakespeare. It depicts the gradual descent into madness of the title character, after he disposes of his kingdom giving bequests to two of his three daughters based on their flattery of him, bringing tragic consequences for all. Derived from the legend of Leir of Britain, a mythological pre-Roman Celtic king, the play has been widely adapted for the stage and motion pictures, with the title role coveted by many of the world's most accomplished actors.

The play was originally drafted in 1605 or 1606. The Tragedy of King Lear, a more theatrical revision, was included in the 1623 First Folio.

After the English Restoration, the play was often revised with a happy, non-tragic ending for audiences who disliked its dark and depressing tone, but since the 19th century Shakespeare's original version has been regarded as one of his supreme achievements. The tragedy is particularly noted for its probing observations on the nature of human suffering and kinship.

William Shakespeare (1564–1616) was an English poet, playwright and actor, widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. His extant works, including some collaborations, consist of about 38 plays, 154 sonnets, two long narrative poems, and a few other verses. His plays have been translated into every major living language and are performed more often than those of any other playwright.

Shakespeare was a respected poet and playwright in his own day, but his reputation did not rise to its present heights until the 19th century. His plays remain highly popular today and are constantly studied, performed, and reinterpreted in diverse cultural and political contexts throughout the world.

In 2016, celebrations will commence in the United Kingdom and across the world to honour The Bard's 400th anniversary.