King John is perhaps the worst king in history, I believe.
-King John had many quarrels with the current pope of the time.
-King John taxed the country heavily after being defeated by France.
-King John starved those who opposed him.
-King John is said to have killed Arthur of Brittany, his nephew.
-King John put innocent people in jail only to steal their belongings.
Hope this helped. Message me if you need anything.