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