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