John, the youngest
son of
Henry II and
Eleanor of Aquitaine, came to the throne of
England after the death of his brother
Richard I in
1199. In practice, John had been ruling for some time before that, as Richard spent most of his reign on
Crusade or defending
Normandy. John had been the favorite of both his parents, but was nicknamed "John Lackland" because he was not given any dukedoms in his youth (available titles and lands had mostly gone to his four older
brothers before the oldest three died). Richard gave him titles and named him
heir to the
throne (rather than Arthur, duke of Brittany and son of their older brother Geoffrey, who strictly speaking had a better claim because of
primogeniture).
John was a man with very few principles; he probably had Arthur murdered in 1203 (which angered the King of France enough to invade Normandy over it) and is also said to have hanged one of his wife's lovers over her bed (though he was known as a womanizer himself). He also quarreled with the Church over who had the power to nominate people for the position of bishop, and was excommunicated in 1208 for it (though he was accepted back into the church in 1213 when he humbled himself before the Pope's choice for Archbishop of Canterbury).
While John was in France in 1214, his nobles gathered together (under the same Archbishop of Canterbury) to protest his misgovernment, and on John's return forced him to sign the Great Charter (Magna Carta) to recognize the rights of the Church, the barons, and the people of England. John, saying that he had signed under duress, got the Pope's permission to raise an army to fight the barons. The fighting went on for about a year with no clear winner. During the fighting, John's baggage train was swept away while crossing a river and John got extremely upset at losing valuables including his crown. He came down with a fever, which was probably not helped by his emotional state, ate too many peaches with new cider and got dysentery from it, and died a few days later on 18 October 1216. He was succeeded by his son Henry III.
John is known as the archetypical bad king, though he was capable of occasionally showing mercy or generosity toward people. I've heard a story that because of this John's reputation, no likely heir to the throne of England is ever named John (however, I can't find any confirmation of this).