Frost Giants are one of the six "core" breeds of Giant in the worlds of Dungeons & Dragons. As their name suggests, they are a borderline elemental species, heavily associated with arctic temperatures; high mountains, glaciers, tundras, taigas... if it's wintery all year around, that's where you'll find Frost Giants. Ironically, despite this, frost giants in Advanced Dungeons & Dragons are not said to be incapable of handling high temperatures; that trait belongs to Ice Giants, an alternative version of the species native to the setting of Birthright. They can be distinguished by their snow-white or ivory colored skin, and light blue or dirty yellow hair and eyes.
Like Fire Giants, these giants hail from Norse Mythology, and as such come with a basic society tacked on: they're giant evil vikings. That's... basically it. Take all your pulpy Nordic warrior tropes, mix with "big evil thug" tropes, and you've got D&D frost giants through the ages. One of their odder traits is that they like to capture and tame other wintery monsters to serve them, such as winter wolves, yeti, remorhaz and even white dragons. Frost Giants value strength above all else, and their Ordnings are based on sheer physical might, usually expressed in wrestling, hunting, or one-on-one combat.
Frost Giants generally worship Thrym, but they are not immune to temptation. Kostchtchie is the Demon Prince of Frost Giants and has conquered many tribes in his efforts to usurp Thrym. Vaprak, deity of ogres and trolls, has a unique gift for Frost Giants who worship him: becoming an Everlasting One. Frost Giant ordnings are based one's own might, and there are no shortcuts; weapons can break, armor can be pierced, and magic items can be disenchanted, so there's no place for them in the Frost Giants' ordnings. Sometimes, a frost giant whose muscles can't match their ambitions will turn to Vaprak, who in exchange for worship will give the giant a strength boost and the regeneration of a troll, thus allowing them a major boost in status that will almost certainly let them become their tribe's Jarl.
Of course, worshipping any of these non-giant gods is an incredibly maug act, certain to make the giant in question an outcast if they're discovered. Everlasting Ones are especially prone to this, as if they displease Vaprak, he might corrupt their regeneration so that their wounds heal with obvious mutations, from gaining warty skin like a troll to even growing extra limbs, making their cheating impossible to hide from their fellows, who obviously are going to be a little twigged off by the Everlasting One's betrayal of all they stand for.