I think that it is generally believed that Richard III was responsible for the death of his nephews Edward V and his brother Richard, the Duke of York, and usurping the throne of England.
There is a theory out there though, that Richard actually believed that he was doing the right thing by taking the throne, when he found out that his nephew may not be the rightful heir because of being illegitimate due to their father's previous marriage, and which made Richard the true heir to the throne. Also, this theory holds that Richard was not the one who had the princes killed, but it was done on the orders of Henry Tudor, who wanted to discredit Richard and pave the way to the throne for himself.
I am curious what others think about this. Thanks.