Sif is a character appearing in American comic books published by Marvel Comics. Created by Stan Lee and Jack Kirby, the character first appeared in Journey into Mystery #102. She is based on the Norse goddess Sif. As an Asgardian warrior and lover of Thor, Sif often accompanies him into battle. She has also battled alongside Balder, who has developed an unrequited attraction to her, as she never shows affection for anyone but Thor and certain individuals who have proved worthy to wield his hammer, Mjolnir, such as the noble alien warrior Beta Ray Bill, and the mortal Eric Masterson.

Asgard is a fictional realm and its capital city appearing in American comic books published by Marvel Comics. Created by Stan Lee, Larry Lieber and Jack Kirby, the realm first appeared in Journey into Mystery #85. Based on the realm of the same name from Germanic mythology, Asgard is home to the Asgardians and other beings adapted from Norse mythology. It features prominently in stories that follow the Marvel Comics superhero Thor.