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