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