Loki Laufeyson, or Loki Odinson, is the biological son of King Laufey, the ruler of the Frost Giants in Jotunheim. Shortly after his birth, Loki was then abandoned and left to die. Found by the Asgardian King Odin, he was taken to Asgard and raised by Odin and his wife Frigga as an Asgardian prince, along with their true biological son Thor.
Real Name: Loki Laufeyson
Species: Frost Giant
Citizenship: Asgardian, Jotun (formerly)
Date of Birth: 965 A.D.
Portrayed by: Tom Hiddleston
When he grew up, he became known as the "God of Mischief". When Thor was to be crowned King, Loki had sabotaged the coronation by letting the Frost Giants attack Asgard, thus leading Thor to seek vengeance on Jotunheim, which resulted on Thor's banishment to Earth and Loki finding the truth about his heritage.
Frigga gave Loki the throne when Odin had fallen into the Odinsleep, however when the Warriors Three and Sif attempted to return Thor home, Loki was forced to try to stop them. Regardless, Thor returned from his exile on Earth and ended Loki's reign.
2. The Avengers
Lost in the darkest depths of the universe, Loki made a deal with The Other, a servant of the Mad Titan Thanos, who gave him a powerful Scepter and command over their army of the Chitauri to conquer Earth.
Once he came to Midgard, Loki managed to take possession of the mystical Tesseract and used its power to open a portal above New York City and caused the Chitauri Invasion, but all of Loki's schemes were ultimately defeated by a new group of superheroes called the Avengers. Thor returned him to Asgard as his prisoner, where Odin condemned him to spend the rest of his life in the Asgardian Dungeons as punishment for his crimes.
3. Thor: The Dark World
However, when his mother Frigga was killed during the Sacking of Asgard, Loki was freed by Thor in order to defeat the Dark Elves and their leader, Malekith who desired to use the power of the Aether to transform the universe into eternal darkness.
During the fight against the Dark Elves in Svartalfheim, Loki faked his death, and, unbeknownst to everyone in the Kingdom, returned to Asgard and successfully removed Odin from the throne, taking his place as King where he remained for several years. During his reign, Loki continued to rule Asgard by sending Lady Sif on missions to Earth to investigate the attacks of Lorelei and Vin-Tak.
4. Thor: Ragnarok
Eventually, the return of Thor forced Loki to reveal his deception as the pair journeyed together to find Odin, arriving just in time to witness Odin's death. The loss of Odin allowed Hela, Odin's first born, to return from banishment and wage war against the Nine Realms.
Loki was found himself at Sakaar along with Thor where Loki allied himself with the Grandmaster while Thor was forced to battle against the Hulk. Despite trying to manipulate his way to freedom, Loki chose to side with Thor and the Revengers in a final battle against Hela, in which Loki summoned Surtur, who defeated Hela by causing Ragnarök and destroying all of Asgard.
During his final moments on Asgard, Loki took the Tesseract from Odin's Vault and in the wake of the Destruction of Asgard, chose to stay by his brother's side and support his ascension onto the throne.
5. Avengers: Infinity War
Consequences of his deal with Thanos would soon come back to haunt Loki, however, as the Mad Titan and his Black Order intercepted the Asgardians as they were making their way towards Earth.
In the chaos that followed, Loki attempted to kill the Mad Titan, who responded by lifting him off his feet. Taunting Thanos by telling him that he would never be a god, Thanos snapped his neck, ending the reign of the God of Mischief.