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