Giants, Dwarves and Elves also play big parts - not just as PC's but as god like beings and servants of the Gods.

Kobolds are a Northern Germanic monster.  

But the main thing is their relationship with the Gods is a bit different.  They Greco-romans thought the Gods lived far away and worshiped.  The Norse Gods were a bit less inhuman.  They didn't have big temples, more like stories told about ancestors that got more and more exaggerated.  They were friendlier with their Gods.  They kind of expected to meet them.  That stranger walking through town could be Thor.  

They had druid/nymph/sylphs called Huldra

They had Fossegrimen male water spirits that played the Fiddle and were kind of Fey (not exactly evil but if you failed them they would punish you ridiculously.

Mares - Nightmarish witches that sat on you while they killed you in your dreams.

Magical Squirrels that causes havoc between an Eagle and Dragon at opposite ends of the Tree of Life.

giants and stuff

I feel like a lot of people forget about how there are giants in Norse mythology and that is another monster you could include in it.

i have long tried to find a way for various monsteres to have the impossible propportions and power that they have in stories. once i made a sea monster that was a regular shark. with 18 intelligince. as a bonus action it could curse a target, and that target would later tell a story of the sea monster and yadda yadda yadda, teh point is whilethe creature was cursed and telling stories, the sea monster grew to be enormous and almost like a kraken. i think this is a cool mechanic and it seems like something you could use