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