Richard's crimes... and Shakespeare's (?)
Richard has acquired a lot of supporters in recent years, all of whom seem to think they're the only one (whenever there's a documentary saying he was a nice guy they pretend nobody's ever said it before); quite a few blame Shakespeare for the creation of the negative image. Let's go through the alleged crimes of Richard one by one and see how true that is.
Killing Edward of Lancaster: The chroniclers mostly say Edward died in battle. Only one, Hall, says that he was captured, and that Edward IV knocked him down before Richard, Clarence, Dorset and Hastings stabbed him. In 3H6, Shakespeare changes this to just the York brothers, Clarence delivering the coup de grace; but in R3 he excuses Edward and Clarence. Afraid we do have a libel here.
Killing Henry VI: Let's see - Richard hurried back from Tewkesbury ahead of his brothers to pay a visit to the Tower, and when he came out Henry was dead. Looks pretty damning.
Arranging Clarence's arrest and death: entirely Edward's doing. But blackening Richard's name was not the work of Shakespeare or any Tudor propagandist - it was rumoured even in Edward's lifetime that he was responsible.
Indirectly causing Edward's death from guilt over Clarence: This is a product of Shakespeare's time-compression. In fact Edward outlived Clarence by several years.
Executing Rivers, Vaughan and Gray without due process: guilty as charged.
Executing Hastings on the barely credible grounds shown in the play: Apparently true. It comes almost verbatim from Thomas More, who though certainly pro-Tudor was also a man of conscience and wouldn't report something he didn't sincerely believe. More was well acquainted with Cardinal Morton, an eyewitness to this scene, and almost certainly heard it from him. It's certainly possible that Morton exaggerated for the sake of a better story, but with plenty of other contemporaries still around who could contradict him he would hardly have cut it from whole cloth.
Smearing Edward and his sons with bastardy: False, insofar as it wasn't a smear. The illegality of Edward's marriage to Elizabeth may have been a quibble, but Edward's own dubious parentage was a fact. Still, if Richard were really concerned only to keep the pure line on the throne he'd have wanted Clarence's son to succeed: pressing his own claim this way suggests that his real motive was ambition.
Killing the Princes in the Tower: They disappeared while he was King, and rumours were already current. The other candidates are simply not plausible: if Henry VII had them killed then they must have outlived Richard, so why didn't he produce them alive to disprove the rumours? If it was Buckingham, why didn't Richard expose the truth when he and Buckingham became enemies?
Killing Anne: Her death is at best suspicious, but there's no hard evidence. Richard did, however, start paying court to his niece before Anne was even dead.
In other words, even where Shakespeare did get it wrong the error usually goes right back to before H7's propagandists got to work on it; most of the charges against Richard hold water.