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