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