Here is the full list of all 31 Beowulf achievements worth 1,000 gamerscore. It takes around 15-20 hours to unlock all of the achievements on Xbox 360.
All of the Thane Prisoners have been saved
Successfully collected all Carnal Runes
Successfully collected all Heroic Runes
Successfully performed the Heroic Storm 38 times
8 enemies were killed during a single Heroic Storm
Entire game completed in Legend Difficulty
Enemies were killed with each available Weapon Type
All Legendary Weapons found
All Carnal Upgrades have been obtained
Act Two completed in Legend Difficulty
Max carnal index reached
28 weapons stolen
Perfect Grendel Song performed
Act One completed in Legend Difficulty
Entire game completed in Thane Difficulty
Dragon defeated
All Heroic Upgrades have been obtained
Act Two completed in Thane Difficulty
Hela defeated
Successfully dodged 88 times
Max heroic index reached
Successfully blocked 58 Attacks
Successfully broke 58 Objects
8 enemies were killed using a Pillar
Wolf defeated
8 people were killed within 1 Carnal Fury
58 enemies were killed using bare hands
Multiple enemies were killed with a single attack 28 times
Act One completed in Thane Difficulty
Grendel defeated
Sea Serpent defeated