In Norse mythology, Loki or Loptr is a god or jötunn (or both). Loki is the son of Fárbauti and Laufey, and the brother of Helblindi and Býleistr. By the jötunn Angrboða, Loki is the father of Hel, the wolf Fenrir, and the world serpent Jörmungandr. By his wife Sigyn, Loki is the father of Nari or Narfi. And by the stallion Svaðilfari, Loki is the mother—giving birth in the form of a mare—to the eight-legged horse Sleipnir. In addition, Loki is referred to as the father of Váli in the Prose Edda.

Loki's relation with the gods varies by source. Loki sometimes assists the gods and sometimes causes problems for them. Loki is a shape shifter and in separate incidents he appears in the form of a salmon, mare, seal, a fly, and possibly an elderly woman. Loki's positive relations with the gods end with his role in engineering the death of the god Baldr. Loki is eventually bound by the gods with the entrails of one of his sons.

In both the Poetic Edda and the Prose Edda, the goddess Skaði is responsible for placing a serpent above him while he is bound. The serpent drips venom from above him that Sigyn collects into a bowl; however, she must empty the bowl when it is full, and the venom that drips in the mean time causes Loki to writhe in pain, thereby causing earthquakes. With the onset of Ragnarök, Loki is foretold to slip free from his bonds and to fight against the gods among the forces of the jötnar, at which time he will encounter the god Heimdallr and the two will slay each other.

Thomas William "Tom" Hiddleston (born 9 February 1981) is an English film, television, radio, and stage actor. He trained at the Royal Academy of Dramatic Art (RADA), and he rose to prominence through a number of TV roles and more recently major film roles. He played Loki in the 2011 Marvel Studios film Thor, Captain Nicholls in Steven Spielberg's World War I film War Horse (2011), and also Freddie Page in the British drama The Deep Blue Sea, alongside Rachel Weisz. He played author F. Scott Fitzgerald in the Woody Allen film Midnight in Paris (2011). He returned to his role as Loki in The Avengers (2012) and is set to reprise the character again for Thor 2 (2013).

Hiddleston was born in Westminster, London, to parents Diana Patricia (née Servaes), a former stage manager and arts administrator, and James Norman Hiddleston, a scientist in physical chemistry who was the managing director of a pharmaceutical company. His father is from Greenock, Scotland and his mother from Suffolk, England. He is the middle child with two sisters, Sarah (oldest), a journalist in India, and Emma (youngest), is also an actor. He was raised in Wimbledon, in his early years, and later in Oxford. When Hiddleston was 13, he boarded at Eton College, at the same time that his parents were going through a divorce. "I think I started acting because I found being away at school while my parents were divorcing really distressing." He went on to act at The Dragon School in Oxford, then continued on to the University of Cambridge, where he earned a double first. He graduated from the Royal Academy of Dramatic Art in 2005.

Captain America is a fictional character, a superhero who appears in comic books published by Marvel Comics. The character first appeared in Captain America Comics #1 (cover-dated March 1941), from Marvel Comics' 1940s predecessor, Timely Comics, and was created by Joe Simon and Jack Kirby. As of 2007, an estimated 210 million copies of "Captain America" comic books had been sold in 75 countries. For nearly all of the character's publication history, Captain America was the alter ego of Steve Rogers, a frail young man who was enhanced to the peak of human perfection by an experimental serum in order to aid the United States war effort. Captain America wears a costume that bears an American flag motif, and is armed with an indestructible shield that can be thrown as a weapon.

An intentionally patriotic creation who was often depicted fighting the Axis powers of World War II, Captain America was Timely Comics' most popular character during the wartime period. After the war ended, the character's popularity waned and he disappeared by the 1950s aside from an ill-fated revival in 1953. Captain America was reintroduced during the Silver Age of comics when he was revived from suspended animation by the superhero team the Avengers in The Avengers #4 (March 1964). Since then, Captain America has often led the team, as well as starring in his own series.

Chris Hemsworth (born 11 August 1983) is an Australian actor best known for portraying Thor in the Marvel Studios films Thor (2011) and The Avengers (2012), and Curt Vaughan in The Cabin in the Woods (2012). Hemsworth is set to continue his role as Thor in the upcoming film Thor 2 in 2013. He also starred as Kim Hyde in the Australian soap opera Home and Away. He is the older brother of Liam Hemsworth and the younger brother of Luke Hemsworth, both actors.

Hemsworth was born in Melbourne, the son of Leonie, an English teacher, and Craig Hemsworth, a social-services counselor. He was raised both there and in the Northern Territory, in a little Aboriginal community in the Outback, called Bulman. He has stated, "My earliest memories were on the cattle stations up in the Outback, and then we moved back to Melbourne and then back out there and then back again. Certainly most of my childhood was in Melbourne but probably my most vivid memories were up there in Bulman with crocodiles and buffalo. Very different walks of life." He attended primary school at Southwood Primary school and high school at Heathmont College, before his family again returned to the Northern Territory, and then moved a few years later, to Phillip Island.