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