Klarion is one of the most dangerous magic-users in creation. He originally came to Earth from the other-dimensional realm known as Witch-World in the Beyond Country, pursued by that world's Elder Judges for the crime of stealing the Book of Forbidden Secrets. Though the Demon Etrigan helped him fight off his attackers, Klarion turned on Etrigan and tried to enslave him. The spiteful clashes between Klarion and the Demon have resulted in the Witch Boy's banishment from Earth's dimension on several occasions.

More recently, Klarion teamed with the Contessa to cause chaos in the super-hero community by flip-flopping the ages--the adults in the Justice League of America and Justice Society of America magically became youths, while the teens of Young Justice found themselves transformed into adults. The heroes broke the spell, but Klarion found more idle amusement by temporarily de-aging a band of super-villains. The only creature Klarion seems to care about is his witch-familiar Teekl, a cat from Witch-World who also possesses a natural talent for magic.