Hrímnir is a jǫtunn ("giant") frequently mentioned in Norse mythology. His name may mean either "the one covered with hoarfrost" or "the sooty one." It is not clear whether the name is intended to evoke the frost giants or hrímþursar (jǫtunn).
In the sagas
In Hyndluljóð verse 32 he is the father of Heiðr and Hrossþjófr, but that may be just for alliteration's sake. He is mentioned in Skírnismál verse 28, probably as a typical giant.
He is listed among the jǫtnar in the "Nafnaþulur" section of the Prose Edda.
In Völsunga saga he is the father of Hljóð who Frigg sends to Rerir as a "wish-maid" with the apple that enables his wife to conceive Völsung—and subsequently Hrímnir himself sends Hljóð to Völsung to be his wife. This resembles the story of Peredur in the Matter of Britain, and the modern folktale "The Sea-Maiden."
In Gríms saga loðinkinna, he is the father of the giantesses Feima and Kleima; his wife's name is Hyrja.