Here is the full list of all 39 Vikings - there are Wolves of Midgard achievements.
Complete all Challenges on all maps.
Complete the game as the Warrior.
Complete Campaign 3.
All Hunt maps complete.
Complete all Trials.
Found all Legendary Items.
Unlock level 4 of the Shipmaster.
Unlock level 5 of the Smithy.
Earn 50,000 gold by selling resources.
Kill 100 Jotun.
Complete the Imp Hunt.
Become chieftain of all the clans.
Complete Campaign 2.
Burn the Imperial Fleet.
Earn 1,000,000 Blood.
Equip three runes on a single item.
Unlock all Gifts in Odin's gift tree.
Unlock all Gifts in Tyr's gift tree.
Unlock all Gifts in Loki's gift tree.
Unlock all Gifts in Thor's gift tree.
Unlock all Gifts in Skathi's gift tree.
Liberate Flotnar village.
Keep Draupnir for yourself.
Complete Campaign 1.
Travel to Utgard.
Survive the Mire-Witch's spell.
Kill four foes in a single attack.
Killed 500 Tomte.
Complete any Hunt map.
Defeat the Jokul.
Perform 1000 rolls.
Defend Ulfung Village.
Complete the game as the Shieldmaiden.
Complete Game+.
Rage continuously for over 20 seconds.
Complete the game on the highest difficulty.
Collect one of every rune.
Accomplish campaign in Valhalla Mode
Accomplish campaign in Valhalla Mode on highest difficulty.