Minnesotans, Giant Lumberjacks, Giant Blue Oxen.
Icicle Piercer
Ice Mite Swarm
Giant Moose (though even a normal moose is pretty darn formidable)
Two mimics in the form of snow shoes
Wendigo (I believe this was stated up in a thread on this site
Thunderbird (stat a roc with natural spell casting allowing it to cast lightning, thunderwave, etc.)
Stone golums, stone giants, galeb dur, and other stone/earth creatures should be fine
Ice Elemental - I would take the earth elemental, give it ice glide allowing it to move through ice and snow. Make it immune to cold damage. Vulnerable to fire damage and thunder damage.
Undead should be unaffected by the cold
woolly mammoths, just restate an elephant. Make it resistant to cold damage.
Oh, don't forget walrus. Both the normal animal and giant walrus. Google walrus attacks. In real life they are known to attack humans and boat, including breaking through ice to attack.
Same with sea lions and leopard seals. I doubt that they can break through ice, but it may wait to ambush any creature at the edge of the ice.
The bowhead whale could be a hazzard. While they are baleen whales they are adapted to break through the ice to breath. It would be a bad day for anyone walking on that ice.
Qalupalik (
https://www.adn.com/features/articl...-mythical-creatures-last-frontier/2012/06/13/)
I would stat up using sea hag stats and add appropriate resistances and abilities but also add the harpy's luring song ability
Adlet (same link as Qalupalik) - basically an arctic werewolf. Just take the werewolf and add cold resistance. Or even immunity from cold damage. Perhaps add some cold damage to its natural bite and claw attacks.