Appearing as early as 1949 in Marvel's Venus #6, mischief maker Loki made his first official appearance in 1962's Journey into Mystery #85 and has since been a consistent foil to Thor and the Avengers.
Loki made his onscreen debut in 1966 as part of the Thor segments of The Marvel Super Heroes donning his trademark long horned helmet.
In the 80's Loki returned to torment Spider-Man and His Amazing Friends in the episode episode "The Vengeance of Loki."
It would be more than 25 years until Loki returned, this time as the antagonist in the animated direct-to-video film Hulk vs. Thor where Loki played puppet master to a mindless Hulk.
In 2011's Thor: Tales of Asgard, although a tad ornery, the young Loki played a young trickster allied with Thor. 2011 would be a big year for old Lokster.
Loki next appeared in The Super Hero Squad Show episode "Oh Brother," appropriately with his brother Thor.
In the 2011 live-action Thor film, Loki was behind all of the film's shenanigans, eventually falling from Asgard.
In 2012, Loki has returned not only seeking revenge against his brother, but with plans to take on the combined might of the Avengers.