structural:summarization, information:extraction, structural:reformatting, information:classification
Changes from source material

Besides the subplot involving the Earl of Gloucester and his sons, the principal innovation Shakespeare made to this story was the death of Cordelia and Lear at the end; in the account by Geoffrey of Monmouth, Cordelia restores Lear to the throne, and succeeds him as ruler after his death. During the 17th century, Shakespeare's tragic ending was much criticised and alternative versions were written by Nahum Tate, in which the leading characters survived and Edgar and Cordelia were married (despite the fact that Cordelia was previously betrothed to the King of France). As Harold Bloom states: "Tate's version held the stage for almost 150 years, until Edmund Kean reinstated the play's tragic ending in 1823."

Holinshed states that the story is set when Joash was King of Judah (c. 800 BC), while Shakespeare avoids dating the setting, only suggesting that it is sometime in the pre-Christian era (with numerous anachronisms, such as Anglo-Saxon names and titles like Duke and Earl).

The characters of Earl "Caius" of Kent and The Fool were created wholly by Shakespeare in order to engage in character-driven conversations with Lear. Oswald the steward, the confidant of Goneril, was created as a similar expository device.

Shakespeare's Lear and other characters make oaths to Jupiter, Juno, and Apollo. While the presence of Roman religion in Britain is technically an anachronism, nothing was known about any religion that existed in Britain at the time of Lear's alleged life.

Holinshed identifies the personal names of the Duke of Albany (Maglanus), the Duke of Cornwall (Henninus), and the Gallic/French leader (Aganippus). Shakespeare refers to these characters by their titles only, and also changes the nature of Albany from a villain to a hero, by reassigning Albany's wicked deeds to Cornwall. Maglanus and Henninus are killed in the final battle, but are survived by their sons Margan and Cunedag. In Shakespeare's version, Cornwall is killed by a servant who objects to the torture of the Earl of Gloucester, while Albany is one of the few surviving main characters. Isaac Asimov surmised that this alteration was due to the title Duke of Albany being held in 1606 by Prince Charles, the younger son of Shakespeare's benefactor King James. However, this explanation is faulty, because James' older son, Prince Henry, held the title Duke of Cornwall at the same time.