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