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