King John was a British king after the supposed death of Richard I. When he became king, he began to make himself even richer by taxing people until they had nothing left to pay. When he discovered this, he didn't care and just rose the taxes. Instead, he imprisoned his enemies and sometimes his own people whenever he felt like it. One reason why was he felt that just because he was king, he could do whatever he felt like doing. However, when he signed the Magna Carta, he tried to break his promise, but then died.
In culture
King John is the main antagonist in the 1973 film Robin Hood. In the film, he is not yet a king, but is called "Prince John" and was voiced by Peter Ustinov. This version is the brother of King Richard and is a coward and a crybaby. Like his real life counterpart, he was very greedy and accompanied by the Sheriff of Nottingham.