One of the armies I painted last year was a dark age style Varangur one. A large chunk of the initial build were draugr kitbashed from warlord dacians & mantic zombies.
Going add a few similar themed undead units (as I don’t have enough armies!) so coming up with a few mock ups.
Skeletons are the Oathmark ones (will get some if the mantic spearmen and give round shields as well), revenants are skeleton/gripping beast viking mix, the soul reavers Victrix Saxon/vikings.
Have some gw crypt horrors as zombie trolls and a bunch of the floaty undead things which can fit as wraiths/wights.