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