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