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