Tom Hiddleston is a good casting choice for Loki because, despite being 42 years old, he looks far younger and can portray the character's youthful appearance. Based on calculations from a Tumblr user, Loki is around 16 "human" years old in the Marvel Cinematic Universe, which explains his petulance in his early appearances. In the comics, Loki's age is more uncertain due to time-traveling and shifting storylines, but it's safe to say he and Thor are much older than their movie counterparts.

While it is standard practice for older actors to portray younger characters, sometimes with hilarious results, there probably isn't an actor alive who could accurately convey how old Tom Hiddleston's Loki is in the MCU. Thankfully, Loki is a god and possesses the enviable ability to maintain his youthful appearance despite his age. Aside from the fact that Hiddleston turned Loki into one of the most iconic MCU characters worthy of his own solo series,...