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