Full list of all 41 Dark Souls achievements worth 1,000 gamerscore. It takes around 80-100 hours to unlock all of the achievements on Xbox 360.
Defeat Crossbreed Priscilla, the Lifehunter.
Defeat Dark Sun Gwyndolin, the Darkmoon God.
Defeat Seath the Scaleless, inheritors of souls.
Defeat the Four Kings, inheritors of souls.
Defeat the Soul Lord Bed of Chaos.
Defeat the Soul Lord Gravelord Nito.
Discover Path of the Dragon covenant.
Discover Gravelord Servant covenant.
Discover Chaos Servant covenant.
Acquire best weapon through lightning reinforcement.
Acquire best weapon through raw reinforcement.
Acquire best weapon through enchanted reinforcement.
Acquire best weapon through divine reinforcement.
Light bonfire flame.
Acquire Estus Flask.
Arrive in Lordran.
Ring Bell of Awakening at Undead Church.
Ring Bell of Awakening in Quelaag's domain.
Acquire the Rite of Kindling.
Acquire the Art of Abysswalking.
Arrive in Anor Londo.
Acquire the Lordvessel.
Discover Darkwraith covenant.
Discover Princess's Guard covenant.
Reach "The Dark Lord" ending.
Acquire all sorceries.
Discover Way of White covenant.
All achievements completed. Congratulations!
Reach "To Link the Fire" ending.
Acquire all rare weapons.
Acquire all pyromancies.
Acquire all miracles.
Discover Blade of the Darkmoon covenant.
Discover Warrior of Sunlight covenant.
Discover Forest Hunter covenant.
Acquire best weapon through standard reinforcement.
Acquire best weapon through crystal reinforcement.
Acquire best weapon through magic reinforcement.
Acquire best weapon through occult reinforcement.
Acquire best weapon through fire reinforcement.
Acquire best weapon through chaos reinforcement.