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