Ice Giants are large creatures found in Treachery, the Ninth Circle in hell.
It is unknown where they range in Treachery, but it seems most likely in Caina and before Judecca, the final region of Treachery before Cocytus, where Lucifer is imprisoned.
In the video game, the Giants try to hinder Dante's progress towards Lucifer by blowing their icy breath towards him.
They are not fully seen in the game, but they are seen in the Animated Epic in a brief cameo appearance. In the cameo, they appear as giant (though their exact depiction of their size isn't clear, mainly because it was never shown of Dante encountering them directly), bony creatures with skeletons formed of jagged ice with sharp edges pointing out to signify their limbs. They do have a head and a face, which expresses an evil expression, with downward-pointing diagonal directed eye-spots and a sinister smile, which both light up neon bluish-green in the dark.