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