From the Wikipedia page on Thomas More [1]:

Between 1512 and 1519, Thomas More worked on a History of King Richard III, which was never finished, but which greatly influenced William Shakespeare's play Richard III. Both More's and Shakespeare's works are controversial to contemporary historians for their unflattering portrait of King Richard III, a bias partly due to both authors' allegiance to the reigning Tudor dynasty that wrested the throne from Richard III in the Wars of the Roses. More's work, however, little mentions King Henry VII, the first Tudor king, perhaps for having persecuted his father, Sir John More. Some historians see an attack on royal tyranny, rather than on Richard III himself or on the House of York.

The History of King Richard III is a Renaissance history, remarkable more for its literary skill and adherence to classical precepts than for its historical accuracy. More's work, and that of contemporary historian Polydore Vergil, reflects a move from mundane medieval chronicles to a dramatic writing style; for example, the shadowy King Richard is an outstanding, archetypal tyrant drawn from the pages of Sallust, and should be read as a meditation on power and corruption as well as a history of the reign of Richard III. The History of King Richard III was written and published in both English and Latin, each written separately, and with information deleted from the Latin edition to suit a European readership.