Richard III is a play by William Shakespeare, in which the monarch Richard III of England is unflatteringly depicted. Critics have argued that this is because the ruling monarch of Shakespeare's time, Elizabeth I, was a descendant of Henry VII of England who had defeated the last Yorkist king and started the Tudor dynasty. Shakespeare's "history" plays were not, however, intended to be historically accurate -- this would have been an outlandish concept for the time -- but were designed for entertainment. As with Macbeth, Richard's supposed villainy is depicted as extreme in order to achieve maximum dramatic effect. The playwright never concerned himself with the veracity of his sources.
The play opens with the famous speech by Richard, beginning, Now is the winter of our discontent... The speech reveals Richard's jealousy and ambition, as his brother, Edward IV of England, rules the country successfully. With little attempt at chronological accuracy, Richard is shown ingratiating himself with "the Lady Anne" -- Anne Neville, widow of the Lancastrian Prince of Wales. Despite her prejudice against him, Anne is won over by his pleas and agrees to marry him. Richard, in collaboration with his friend Buckingham (Henry Stafford, Duke of Buckingham), plots to be the next king, and presents himself to the other lords as a modest, devout man with no pretensions to greatness. This causes them to select him as king after Edward IV's death, putting aside the claims of his innocent young nephews (the Princes in the Tower).
Richard's crimes go from bad to worse. He murders all who stand in his way, including the young princes, Lord Hastings, his former ally Buckingham, and even his wife. When he has lost all popular support, he faces the invading Earl of Richmond (Henry VII) at the Battle of Bosworth Field. Prior to the battle, Richard is visited by the ghosts of those whose deaths he has caused, all of whom tell him to Despair and die! Alone on the field at the climax of the battle, he utters the often-quoted line, A horse, a horse, my kingdom for a horse! He is defeated in hand-to-hand combat by Richmond, and dies dramatically.
Shakespeare's main source for his play was the chronicle of Raphael Holinshed but it also seems likely that he drew on the work of Sir Thomas More author of the unfinished 'History of King Richard III' published by John Rastell after More's death. Rastell, More's son in law, compiled the text from two work-in-progress manuscripts, one in English and one in Latin in different stages of composition. More's work is not a history in the modern sense. It is a highly coloured and literary account which contains accurate and invented details in (arguably) roughly equal portions. More had many sources available for his account (most of whom, like his patron Cardinal John Morton were extremely hostile to the old regime) but like Shakespeare his main source is his own imagination: over a third of the text consists of invented speeches.
Richard III is the culmination of the cycle of Wars of the Roses plays. In Henry VI Part III, Shakespeare had already begun the process of building Richard's character into that of a villain, even though he could not possibly have been involved in some of the events depicted. From an overview of the cycle, it can be seen that Shakespeare's inaccuracy works both ways.
The most famous player of the part in recent times was Sir Laurence Olivier in the 1950s film version. His inimitable rendition has been satirised by many comedians including Peter Cook, and Peter Sellers (who had aspirations to do the role straight). Sellers' version of A Hard Day's Night was delivered in the style of Olivier as Richard III.
More recently, Shakespeare's Richard III has been brought to the screen by Sir Ian McKellen (1995) in an abbreviated version set in a 1930s fascist England (see Richard III (movie, 1995)), and by Al Pacino in the 1997 documentary, Looking for Richard.