Here is the full list of all 57 Star Wars Knights of the Old Republic II: The Sith Lords achievements.
Defeat Sion
Claim Darth Nihilus' mask.
Defeat Nihilus
Side with the Settlers at Khoonda
Recruit the Disciple
Get the named Lightsaber crystal
Win a Pazaak game with a full board
Learn Moving Meditation
Gain a Prestige class
Complete the game on the Light Side
Acquire all Light Side Powers
Install HK-47's unique module
Fill the Party Selection screen
Complete the Mandalorian Battle Circle
Learn how to kill Jedi from HK-47
Have 30 points in Stealth
Convince Vogga the Hutt to sell fuel to Telos.
Recruit Mira
Have Persuasion over 30
Have 30 points in Repair.
Have 30 points in Computer Use.
Repair the damaged droid on the Ebon Hawk
Teach the Handmaiden the ways of the Force.
Learn Force Sight
Contruct your first Lightsaber
Flee Korriban after fighting Sion
Get this by starting the "Trapped" Quest on Korriban.
Loot a body on Korriban
Recruit the Handmaiden
Complete the Handmaiden Battle Circle
Collect 10,000 credits
Destroy Peragus Astroids
Reach Player Level 30
Have 30 points in Demolitions.
Have 30 points in Treat Injury.
Reach maximum Light Side points
Reach maximum Dark Side points
Get your first Light Side points
Let the Sith destroy the Peragus Asteroids
Kill all Sith troopers before they can board the Ebon Hawk
Dance for Vogga
Get your first Dark Side points
Complete the Prologue
Complete the game on the Dark Side
Side with the Queen on Onderon
Side with Vaklu on Onderon
Recruit Hanharr
Break Hanharr's spirit
Beat the champ on Nar Shadaa
Change your mind about siding with the Settlers at Khoonda
Reduce a companion's Influence to zero.
Acquire all Dark 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.
Deduce G0-T0's identity
Listen to HK-47's definition of love.