Richard D.

In 1399, after John of Gaunt died, the king disinherited Gaunt's son, Henry of Bolingbroke, who had previously been exiled. Meeting little resistance, Bolingbroke deposed Richard and had himself crowned as King Henry IV. Though probably not insane, as earlier historians used to believe, he may have suffered from what modern psychologists would call a "personality disorder" towards the end of his reign.