Charles VI of France
Charles VI has gone down in history as both "Charles the Beloved" and "Charles the Mad." So how did he get both titles?
He received the first after restoring order to France. He became king at age 11 in 1368, but his uncles ruled until he was 21, ruining the finances of the country and causing numerous revolts. Charles then took over, got rid of the uncles and reinstated his father's trusted advisers [sources: Columbia Electronic Encyclopedia, France.fr].
Unfortunately, the happy period only lasted about four years before he began to earn his second title.
While pursuing the man who attempted to assassinate an adviser, Charles became convinced that he was being chased by enemies. Ultimately he killed several of his own knights and nearly murdered his brother. His periods of lucidity became briefer over the years, as he sometimes did not recognize his wife or family, or didn't even remember that he was the king. He went long periods without bathing, ran through the corridors of his palace at all hours, and claimed that he was Saint George [source: Rohl et al.].
But Charles VI's most famous delusion was that his body was made of glass. He refused to be touched and required that special protective clothing be made to keep him from shattering [sources: Fink and Tasman, Sommerville]. Today it's thought that he probably had bipolar disorder, but at the time his illness was considered God's will because he had supported the antipope Clement VII [source: Fink and Tasman].