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