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