Thor is the "God of Thunder", a member of the race known as the Asgardians, a group of humanoid beings from the pocket dimension of Asgard, the Realm Eternal. Thor is the son of Odin, the All-Father and king of Asgard. He was worshiped by the humans known as Vikings and became part of Norse Mythology.Armed with his enchanted Uru hammer Mjolnir, which helps him to channel his godly energies, he became the mightiest warrior in the Ten Realms. When his irresponsible and impetuous behavior became too much, Odin sent him to Midgard (more commonly known as Earth) as a disabled mortal medical student named Donald Blake, stripped of his memory. After learning humility he regained his memory as well as his godly powers.Thor went on to become a champion for Midgard as well as one of the founding members of the Avengers, "Earth's Mightiest Heroes".
Doctor Stephen Vincent Strange M.D., Ph.D is the former Sorcerer Supreme and Master of the Mystic Arts. Originally being a brilliant but arrogant neurosurgeon, Strange got into a car accident which resulted with his hands becoming crippled. Once Western medicine failed him, Strange embarked on a journey to Kamar-Taj, where he was trained by the Ancient One in the ways of Magic and the Multiverse. Although he focused on healing his hands, Strange was drawn into a conflict with Kaecilius and the Zealots, who were working for Dormammu and had sought to merge Earth with the Dark Dimension to find an eternal life. Following the demise of the Ancient One and the defeat of Kaecilius, Strange then became the new protector for the Sanctum Sanctorum, seeking to defend the Earth from other inter-dimensional threats.
Clinton Francis "Clint" Barton is an extremely skilled marksman, a former special agent of S.H.I.E.L.D. and one of the founding members of the Avengers. Known for his use of the bow and arrow as his primary weapon and an extremely keen eyesight and accuracy that earned him the codename Hawkeye, Barton had become one of the best agents of S.H.I.E.L.D., responsible for the recruitment of Black Widow, whom he developed a strong friendship with. Assigned by Nick Fury into watching over the Tesseract, he was brainwashed by Loki and used as his pawn in his attempt to become king of Midgard. However, following their Attack on the Helicarrier, he was freed from Loki's mental controls by Black Widow and joined the Avengers to fight against Loki's Chitauri army in the battle of New York, ending Loki's invasion, before Hawkeye had returned to his work at a S.H.I.E.L.D..
Groot is a Flora colossus and the accomplice of Rocket Raccoon. Together, the pair had traveled the galaxy picking up bounties until they met Star-Lord and Gamora just before the four of them were captured and put into the Kyln, where they also met Drax the Destroyer. There, they agreed to work together to escape and sell the Orb for a massive profit. However, when it was discovered that the Orb contained one of the Infinity Stones which was being sought out by Ronan the Accuser, Groot convinced his friends to risk everything to stop Ronan's diabolical plans. During the Battle of Xandar, Groot sacrificed his own life to save his new friends. However, part of his destroyed body was planted by Rocket to birth a new Groot, as they joined the Guardians of the Galaxy.