Question: Which character did Richard Burbage play that is derived from the legend of Leir of Britain?

full_context: Document 1: Leir of Britain: Leir was a legendary king of the Britons whose story was recounted by Geoffrey of Monmouth in his pseudohistorical 12th-century "History of the Kings of Britain". According to Geoffrey's genealogy of the British dynasty, Leir's reign would have occurred around the 8th century BC, around the time of the founding of Rome. The story was modified and retold by William Shakespeare in his Jacobean tragedy "King Lear".
Document 2: The Tragedy of King Lear (screenplay): The Tragedy of King Lear is an unpublished screenplay by Harold Pinter. It is an adaptation of William Shakespeare's "King Lear" and was commissioned by actor and director Tim Roth with backing from Film Four. Pinter completed the screenplay on 31 March 2000, but as of 2017 it has not yet been filmed. It is one of only three screenplays that Pinter adapted from another dramatist's play; the others being his screenplay adaptation of "Butley", by his good friend Simon Gray, and "Sleuth", originally written for the stage by Anthony Shaffer.
Document 3: Cordelia (King Lear): Cordelia is a fictional character in William Shakespeare's tragic play, "King Lear". She is the youngest of King Lear's three daughters, and his favourite. After her elderly father offers her the opportunity to profess her love to him in return for one third of the land in his kingdom, she refuses and is banished for the majority of the play.
Document 4: King Lear (1987 film): King Lear is a 1987 film directed by Jean-Luc Godard, an adaptation of Shakespeare's play in the style of experimental French New Wave cinema. The script was primarily by Peter Sellars and Tom Luddy, and was originally assigned to Norman Mailer. It is not a typical cinematic adaptation of Shakespeare's tragedy "King Lear", although some lines from the play are used in the film. Only three characters – Lear, Cordelia and Edgar – are common to both, and only Act I, scene 1 is given a conventional cinematic treatment in that two or three people actually engage in relatively meaningful dialogue.
Document 5: Shakespeare in performance: Thousands (perhaps even millions) of performances of William Shakespeare's plays have been staged since the end of the 16th century. While Shakespeare was alive, many of his greatest plays were performed by the Lord Chamberlain's Men and King's Men acting companies at the Globe and Blackfriars Theatres. Among the actors of these original performances were Richard Burbage (who played the title role in the first performances of "Hamlet", "Othello", "Richard III" and "King Lear"), Richard Cowley, and William Kempe.
Document 6: King Lear (1999 film): King Lear is a 1999 adaptation of William Shakespeare's play of the same name. The film stars Brian Blessed (who also co-directed the film, along with Tony Rotherham) in the title role. Apart from Peter Brook's "King Lear" in 1971, it is the only other feature length film adaptation to preserve Shakespeare's verse. Yvonne Griggs, in "Shakespeare's King Lear: A close study of the relationship between text and film" (2009), characterised it as "a very stilted costume drama".
Document 7: Hamlet on screen: Over fifty films of William Shakespeare's "Hamlet" have been made since 1900. Seven post-war "Hamlet" films have had a theatrical release: Laurence Olivier's "Hamlet" of 1948; Grigori Kozintsev's 1964 Russian adaptation; a film of the John Gielgud-directed 1964 Broadway production, "Richard Burton's Hamlet", which played limited engagements that same year; Tony Richardson's 1969 version (the first in colour) featuring Nicol Williamson as Hamlet and Anthony Hopkins as Claudius; Franco Zeffirelli's 1990 version starring Mel Gibson; Kenneth Branagh's full-text 1996 version; and Michael Almereyda's 2000 modernisation, starring Ethan Hawke.
Document 8: King Lear: 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.
Document 9: Richard Burbage: Richard Burbage (6 January 1567 – 12 March 1619) is considered the first great actor of English theatre. He is one of the most famous actors of the Globe Theatre of his time. In addition to being a stage actor he was also a theatre owner, entrepreneur and painter. He was the younger brother of Cuthbert Burbage. They were both actors in drama. Burbage was a business associate and friend to William Shakespeare.
Document 10: Shakespeare's Globe: Shakespeare's Globe is the complex housing a reconstruction of the Globe Theatre, an Elizabethan playhouse associated with William Shakespeare, in the London Borough of Southwark, on the south bank of the River Thames. The original theatre was built in 1599, destroyed by fire in 1613, rebuilt in 1614, and then demolished in 1644. The modern Globe Theatre reconstruction is an academic approximation based on available evidence of the 1599 and 1614 buildings. It is considered quite realistic, though contemporary safety requirements mean that it accommodates only 1400 spectators compared to the original theatre’s 3000.
Document 11: Shakespearean history: In the First Folio, the plays of William Shakespeare were grouped into three categories: comedies, histories, and tragedies. The histories—along with those of contemporary Renaissance playwrights—help define the genre of history plays. The histories might be more accurately called the "English history plays" and include the outliers "King John" and "Henry VIII" as well as a continuous sequence of eight plays covering the Wars of the Roses. These last are considered to have been composed in two cycles. The so-called first tetralogy, apparently written in the early 1590s, deals with the later part of the struggle and includes "Henry VI, parts one", "two" & "three" and "Richard III". The second tetralogy, finished in 1599 and including "Richard II", "Henry IV, Part 1", "Henry IV, Part 2" and "Henry V", is frequently called the "Henriad" after its protagonist Prince Hal, the future Henry V.
Document 12: William Shakespeare: William Shakespeare ( ; 26 April 1564 (baptised) – 23 April 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. He is often called England's national poet, and the "Bard of Avon". His extant works, including collaborations, consist of approximately 38 plays, 154 sonnets, two long narrative poems, and a few other verses, some of uncertain authorship. His plays have been translated into every major living language and are performed more often than those of any other playwright.
Document 13: Richard Cowley: Richard Cowley (died 1619) was an actor in English Renaissance theatre, a colleague of William Shakespeare and Richard Burbage in the Lord Chamberlain's Men and the King's Men.
Document 14: Goneril: Goneril is a character in Shakespeare's tragic play "King Lear" (1605). She is the eldest of King Lear's three daughters. Along with her sister Regan, Goneril is considered a villain, obsessed with power and overthrowing her elderly father as ruler of the kingdom of Britain. Her aggressiveness is a rare trait for a female character in Elizabethan literature.
Document 15: Richard Sharpe (actor): Richard Sharpe (c. 1602 [?] – January 1632) was an actor with the King's Men, the leading theatre troupe of its time and the company of William Shakespeare and Richard Burbage. Sharpe began his career as a boy player acting female roles, then switched to male roles in his young adulthood.
ground_truth: King Lear