A hero published by Marvel Comics. Beta Ray Bill first appeared in Thor #337 and was created by Walt Simonson.
Thor, the Norse god of thunder and hero of the Marvel Universe, has for years wielded the mystic hammer Mjolnir in battle. The enchantments placed upon the hammer were many, but two in particular are key to our story. First, in an effort to teach Thor humility, Odin placed an enchantment upon the hammer that if it was out of his hand for sixty seconds, Thor would revert to the form of the mortal Donald Blake. The other enchantment was that only one who was worthy could lift and wield Mjolnir. Both of these spells would play into the saga of Beta Ray Bill.
Bill is an alien whose race was part of a huge galactic empire in another galaxy with the unfortunate moniker of the Burning Galaxy. When the evil mystic entity known as Surtur decided to reforge his Sword of Doom, he caused the galactic core of the Burning Galaxy to explode to fuel this process. Bill's people fled in an armada of space ships, seeking a place of safety. Realizing that the armada would likely encounter dangers in its travels, the race began to take likely candidates through a series of grueling physical, mental, and genetic tests in hopes of finding a candidate who they could use to create a guardian for their race. The only survivor of these tests was Bill, who was then subjected to a series of surgeries and genetic manipulations which left him a hulking, muscle bound freak to his own people. His body was enhanced with cybernetics and the genetic manipulation combined Bill's DNA with a vicious predator, giving him an elongated face with a mouth filled with sharp teeth. Bill along with a sentient spaceship known as Skuttlebutt guarded Bill's race while they went into cryogenic sleep for the long journey.
Soon into the journey, Bill discovered that the armada was pursued by a demon horde loosed by Surtur. Bill and Skuttlebutt attempted to fight them but they proved too strong for the pair. About that time, the armada entered the Milky Way galaxy and Thor at the behest of S.H.I.E.L.D. and its director Nick Fury went to investigate. Encountering Bill, the two clashed, Bill seeing Thor as an invader and Thor seeing Bill's monsterous form assumed he was a threat. During the battle, Thor was separated from his hammer and after a minute transformed back into Donald Blake. Bill retrieved Thor's hammer, which had assumed the form of Blake's wooden cane and striking it against the wall, was transformed and filled with the power of Thor. In the form of Beta Ray Thor, Bill was transported to Asgard by Odin by mistake soon after Skuttlebutt crashed on Earth.
Realizing his mistake, Odin transported Thor to Asgard. Bill refused to return Thor's hammer, arguing that he had won it in fair combat and desiring to use it to defend his people. The fact that Bill could wield the hammer showed that he was worthy of it, a fact that Odin never considered. Odin arranged for combat between the two heroes to decide on the fate Mjolnir. Bill bested Thor in combat thereby winning the right to Mjolnir. So that everyone won, Odin had the dwarves who first created Mjolnir to create a new hammer with equal power which was named Storm-breaker and gave it to Bill. Bill, Thor and, the warrior woman Sif returned to Bill's people and defeated the demon hoard. When they returned to Asgard, Odin transfered the enchantment that turned Thor into Donald Blake to Storm-breaker, allowing Bill to return to his original form. He and Sif returned to his people to guard them on their journey.
Since then Bill has aided Asgard in its time of great need, fighting against the demon Surtur when he attempted to destroy Asgard and Earth. Bill and Sif have begun the first stages of a romance.