The Kingdom of Navarre was located in Spain and from 1349-1387 was ruled by Charles the Second.
He is now known as Charles the Bad.
Given that this was the 14th century and brutality was almost expected of Kings, Charles had to have been particularly, well, bad.
Charles was born in France and always felt he had claim on the French throne, although The incumbent obviously disagreed. His nefarious deeds included assasinating the Constable of France and then intriguing with the English against John the second of France to seize the constable's territories (only to then double cross the English). Charles continued to conspire against John II, aiming to replace him with the Dauphin, resulting in him finally being arrested by John in 1356.
Although John was captured by the English himself shortly thereafter Charles was not sprung from prison until 1357. Whereapon he proceeded to make trouble for the Dauphin by demanding Normady be given to him. Losing the negotiation, Charles released all the Paris prisoners, creating anarchy, retreated to Normady and effectively declared civil war with the help of the English.
Paris, as Paris does, erupted into a revolution, kicked out the Dauphin and invited Charles back in. Charles then decided to play both sides against the middle. He gleefully put down a peasant rebellion to the north of Paris, having the leaders beheaded, but tried to encourage the peasants in Paris to support him. This lost him the support of the nobility who defected to the Dauphin. Realising he was outnumbered, Charles was offered substantial cash and land to get the Parisians to surrender. They, distrusting nobility, refused. So Charles deliberately led his forces into an ambush instead and about 600 Parisians were killed.
After this Charles left Paris and tried to open negotiations to join forces with the English (the idea being they would split France between them when the war was over). Unsuprisingly the English weren't so keen on trusting Charles. By 1360 a peace accord was made between all parties, the Dauphin defeated, John II restored to his throne and Charles pardoned and returned his territories in return for mopping up the last of the marauding Anglo-Navarrese mercenaries (most of which he released in the first place).
In 1361 Charles tried to claim the Duchy of Burgundy. John II wasn't too keen on that and there was yet more conflict. Once again Charles was humbled. By 1365 peace was once again declared, but not before substantial loss of life. Charles II topped this all off by poisoning the captain of a mercenary group who had arrived and asked to be paid for his services.
From 1365-1379 Charles continued to try and gain a foothold in France using the Spanish wars and the renewed French-English conflict to do so. Unfortunately none of his machinations came to fruition. In fact, quite the opposite. By 1379, Charles had no French territories left, was the laughing stock of Europe and was reduced to holding only Navarre.
On top of all of that, his health was declining.
Charles had become infected with leprosy, a chronic disease that has been endemic to humanity for thousands of years. Now known to be caused by a bacteria, Mycobacterium leprae, at the time it was no doubt felt to be due to Charles debauchery.
Leprosy is a disease that effects the nerves, skin and eyes, causing numbness in the extremities. Repeated injuries lead to the sterotypical concept of the leper losing parts of themselves.
Reportedly by his mid fifties Charles II had fallen into such a state of decay he could no longer make use of his limbs. To treat his condition, his physicians ordered he be wrapped every night in bandages soaked in brandy.
This dubious treatment was to prove his undoing. According to the tale one night a servant girl, administering the cure, finished wrapping the bandages and saw a stray thread. She took a candle and set a flame to the end, intending to burn it away.
Instead she set her master alight.
Charles the Bad burnt to death.
It was seen by the peasantry to be fair justice for his behaviour and was the substance of morality tales for many, many years to come. (Example here).
I'm sure much of the nobility were glad to see the back of him too.