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