In English folklore, Jack Frost appears as an elfish creature who personifies crisp, cold, winter weather; a variant of Father Winter (also known as "Old Man Winter"). Some believe this representation originated in Viking folklore.
Tradition holds Jack Frost responsible for leaving frosty crystal patterns on windows on cold mornings (window frost or fern frost).
Proponents of Jack Frost's Viking folklore roots state that the English language derives the name "Jack Frost" from the Norse character names, Jokul ("icicle") and Frosti ("frost"). Others see "Jack Frost" as a much more recent import into Anglo-Saxon culture from a Russian fairy tale (see Morozko). In the Finnish epos Kalevala (canto number 30, as translated from Finnish into English by Keith Bosley) Jack Frost appears as the son of Blast, "Pakkanen Puhurin Poika". Other tales in Russia represent frost as Father Frost, a smith who binds water and earth together with heavy chains. Compare the German folklore figure, the old woman Frau Holle, who causes snow by shaking white feathers out of her bed.