The hammer of Marvel superhero Thor is called "Mjolnir." According to Marvel tradition, it was made inside the core of a dying star from a substance known as "Uru," a metal from Thor's home. The hammer weighs 42.3 pounds.
Compared to Earth weapons, Mjolnir is both light and incredibly strong. Thor's father, Odin, leader of the Asgardian gods, had the magical hammer forged for the boy's 8th birthday. However, Thor was not to receive the weapon until he proved himself worthy of it. That process took eight more years of practice and heroic adventures. At one point, Odin banished Thor to Earth for his excessive pride, taking away Thor's powers, memory and hammer.