Jack Frost resembles a young man made of ice, and can create and withstand extremely cold temperatures and generate large amounts of ice. The introduction in his first story implies that he is a mythical creature, a lonely figure existing in the
Arctic landscape: "The far north! Challenging! Mysterious! Foreboding! The land that no man really knows... in this great, frozen waste, surrounded by an eternal, deathly quiet, lives a person we have all heard of but few men have seen — the King of the Cold — Jack Frost!" This spirit was awoken by the cries of a dying prospector, who's been shot by a claim-jumper. In his final moments, the man pleads with Jack to protect his daughter in
New York City, and Jack — horrified by the crime — transports himself to America to confer with the police. They do not believe his story, so he determines to fight evil wherever he can find it. During
World War II, he joined with other superheroes to form the team
Liberty Legion and protect the United States from
Axis home-front infiltration. The Liberty Legion was initially assembled by
Bucky to rescue the
Invaders brainwashed by the
Red Skull. With the Legion, Jack Frost battled
Namor the Sub-Mariner and the original
Human Torch, and protected bystanders from shrapnel with an ice umbrella. Jack Frost was seen again in a 1991 issue of
Captain America, in which it was explained that he had sacrificed himself by melding with a powerful Arctic "ice-worm" monster, in order to neutralize it and keep it from savaging innocent people. Jack Frost was briefly freed during an encounter with Captain America, before willingly being swallowed by and joining with the ice-worm once more.
Thor speculates that Jack Frost may be the diminutive child of a
Norse mythology Frost giant. This was subsequently confirmed in
Scarlet Witch vol.4 #8 (2025) wherein it is revealed he is the son of Buri and an ice giant. ==Powers and abilities==