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