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