Here is the full list of all 38 Dark Souls II achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Earn all achievements
Learn all miracles
Learn all pyromancies
Inherit equipment from the head of Vengarl
Inherit Steady Hand McDuff's equipment
Inherit equipment from Lucatiel of Mirrah
Inherit Benhart of Jugo's equipment
Discover an ancient covenant
Learn all gestures
Discover the covenant of the protectors
Learn all hexes
Learn all sorceries
See the ending
Max-out devotion to covenant
Light all flames on the map in Majula
Increase the population of Majula
Discover the abysmal covenant
Defeat Vendrick
Inherit Captain Drummond's equipment
Acquire Ashen Mist Heart
Discover the clangorous covenant
Discover the covenant of the bloodthirsty
Acquire the King's Ring
Reinforce a weapon to its limit
Defeat Looking Glass Knight
Light the primal bonfire in the Black Gulch
Light the primal bonfire in Brightstone Cove Tseldora
Discover the covenant of rodents
Inherit Laddersmith Gilligan's equipment
Give Rosabeth of Melfia something to wear
Light the primal bonfire in the Iron Keep
Discover a most brilliant covenant
Light the primal bonfire in Sinner's Rise
Defeat the Last Giant
Die for the first time
Discover the covenant of the fittest
Discover the covenant of the meek
Reclaim flesh and set out as an Undead