Beta Ray Bill is a fictional superhero appearing in American comic books published by Marvel Comics. Debuting in the Bronze Age of Comic Books, the character was initially intended to be a surprise; an apparent monster who unexpectedly turns out to be a great hero. As such, Bill is the first being outside the Marvel Universe's Norse pantheon to be introduced as being worthy to wield Thor's hammer, Mjolnir. After an initial rivalry for possession of the weapon, the alien warrior was granted a war hammer of his own, called Stormbreaker, and the two reconciled as staunch allies, going on to fight side by side.
Source: Wikipedia, "[en.wikipedia.org/wiki/Beta_Ray_Bill Beta Ray Bill]", available under the CC-BY-SA License.