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