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