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