Loki Laufeyson (Earth-616)

Loki Laufeyson, generally referred by the mononym Loki, is the Marvel Comics equivalent of the trickser god from Norse mythology. Generally depicted as a supervillain, he was formally integrated into the Marvel Universe in Journey Into Mystery #85 (October 1963). Following on the Arthur C. Clarke adage "Any sufficiently advanced technology is indistinguishable from magic", Jack Kirby and the Lieber brothers reimagined him as an alien who uses advanced technology that appears magical to the people of Earth.

Loki was the first opponent The Avengers faced, and remains one of their greatest individual threats.

Early Life
Loki (nee Hveðrungr) was born on the frozen planet Jotunheim, to King Laufey and Queen Farbauti. Because of his small size and pale skin, he was considered weak by Jotunn standards and the royal family kept them hidden from their subjects. The warlike Jotunn (Frost Giants) soon found themselves in conflict with the Aesir, a humanoid species from the neigboring world of Asgard. Laufey was slain by the Aesir ruler, Odin Borson. Finding Loki hiding within Laufey's castle, Odin took pity on Loki and adopted him. Raised alongside Odin's biological sons, Loki grew up thinking he was an Aesir, and it took years before he learned his true heritage.

Loki came to harbor feelings of jealousy and resentment to his foster brothers, especially Thor, as they embodied the core Asgardian virtues of great strength, tenacity, and bravery, while Loki, lacking in these areas, favored guile, stealth and skill. Earning the nickname "God of Mischief" due to his sneaky nature, Loki gradually became more malicious as he matured, culminating with him tricking the blind, insane Aesir Hðd into shooting Baldur with a poisoned arrow. Seeing this as the final straw, Odin had Loki arrested and imprisoned in Yggdrasil (the World Tree), declaring he would not be freed until someone shed a tear for his plight.

Avengers: The Origin
After centuries of imprisonment, Loki eventually exerted his will on the World Tree, causing a leaf to strike Heimdall, the guardian of Bifrost, in the eye, which made him shed a tear. After learning that Odin had exiled Thor to Midgard (Earth) in an attempt to teach him humility, Loki traveled to the planet, hoping to kill his brother and conquer his adopted homeworld. After a string of early defeats, Loki witnesses one of The Hulk's rampages, and is impressed with the behemoth's power. Setting a trap to lure Thor and the Hulk into a fight, Loki is surprised when Iron Man, Ant Man, and Wasp arrive to save Thor before the Hulk can overpower him. Now facing five superpowered heroes, Loki is defeated, and the quintet, concluding they work well together, form a team, naming themselves the Avengers.

Quotes
"The reason super-criminals fail is that they become obsessed with VENGEANCE. After being beaten by a certain foe, what do you do? You go BACK, only to get BEATEN again. My advice to your team is simple: EXCHANGE OPPONENTS!"

- Loki suggests supervillains switch dance partners once in a while

"Mischief is a small thing, a toy I've well used and discarded. This isn't mischief. This is mayhem. Just watch."

- Loki has decided to up his game