Fire giant Surtur, "Thor 3's" villain, could be one of the MCU's scariest antagonist.

According to Marvel.com, "Surtur was an enormous fiery demon native to the dimension of Asgard. Possessed of evil intelligence and vast power, Surtur was one of the major elemental forces of evil that the Asgardians feared. He was a mystical being whose existence predated that of Odin himself. Over 1,000 feet tall and wielding a huge fiery sword, he was once imprisoned by Odin at the Earth's core. Along with Ymir the Frost Giant and the Midgard Serpent, Surtur was the most powerful of Asgard's native enemies."

"Surtur has been freed from imprisonment a few times over the years. The first time the Asgardian god of mischief Loki set Surtur free to wreak havok on Earth."

As fans might already know, the 3rd installment of the Marvel franchise will be using the Ragnarok plot, where Surtur will destroy all of Asgard that will eventually kill-off major characters including the god of thunder himself.

According to "Thor 3" villain updates published on Movie Pilot, Asgard could come to an end because of Chris Hemsworth's Thor as a part of the "apocalyptic comic book story of Ragnarok."

"After ripping off his brother Loki's head, Thor goes to Muspellheim to meet Surtur after he shattered his hammer and carrying his brother's head," an article in Fashion & Style said.

"The fire giant wants to know whether Thor wants a final battle, but Thor instead convinces Surtur to allow him to reforge his hammer," the website added. "In exchange, Thor smashes down a mountain and lets Surtur lead his army of fire demons onto Asgard. The Norse Valhalla is consumed in fire."

Meanwhile, rumor also has it that the post-credits clip of the "Avengers 2: Age of Ultron" movie will reveal Loki sparking a war between Midgard and Asgard, prompting the start of the Ragnarok.

"Thor 3: Ragnarok" is slated for a July 2017 release.

Stay tuned for more "Thor 3" villain updates here!