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