Here is the full list of all 57 Star Wars Knights of the Old Republic II: The Sith Lords achievements.
Complete the game on the Dark Side
Have your character replace any of the Sith Lords on the main menu screen.
Acquire all Dark Side Powers.
Kill all the Jedi masters
Recruit the Disciple
Reach maximum Dark Side points
Side with Vaklu on Onderon
Flee Korriban after fighting Sion
Break Hanharr's spirit
Recruit Hanharr
Listen to HK-47's definition of love.
Reduce a companion's Influence to zero.
Win a Pazaak game with a full board
Deduce G0-T0's identity
Beat the champ on Nar Shadaa
Convince the "champ" to lose the game without playing.
Let the Sith destroy the Peragus Asteroids
Kill all Sith troopers before they can board the Ebon Hawk
Complete the Handmaiden Battle Circle
Learn how to kill Jedi from HK-47
Change your mind about siding with the Settlers at Khoonda
Teach the Handmaiden the ways of the Force.
Learn Moving Meditation
Complete the game on the Light Side
Defeat Sion
Reach Player Level 30
Claim Darth Nihilus' mask.
Defeat Nihilus
Acquire all Light Side Powers
Install HK-47's unique module
Have 30 points in Demolitions.
Have 30 points in Stealth
Have 30 points in Treat Injury.
Have Persuasion over 30
Learn Force Sight
Side with the Settlers at Khoonda
Get the named Lightsaber crystal
Get this by starting the "Trapped" Quest on Korriban.
Loot a body on Korriban
Side with the Queen on Onderon
Convince Vogga the Hutt to sell fuel to Telos.
Fill the Party Selection screen
Recruit Mira
Have 30 points in Repair.
Have 30 points in Computer Use.
Contruct your first Lightsaber
Repair the damaged droid on the Ebon Hawk
Gain a Prestige class
Reach maximum Light Side points
Complete the Mandalorian Battle Circle
Collect 10,000 credits
Recruit the Handmaiden
Get your first Dark Side points
Destroy Peragus Astroids
Dance for Vogga
Get your first Light Side points
Complete the Prologue