There are 20 unique legacy titles associated with Knights of the Fallen Empire content. 4 are unobtainable.
Alliance Commander is obtained from completing "An Established Alliance" achievement.
Bunker Buster is obtained from completing "Bunker Buster" achievement.
Deathless Champion is obtained from completing "Deathless Champion" achievement.
Deathless Loner is unobtainable.
Eternal Champion is obtained from completing "Eternal Champion" achievement.
Eternal Legend is obtained from completing "Eternal Legend" achievement.
Fallen Knight is obtained from completing "Fallen Knights of the Empire" achievement.
Favored of Darth Marr is unobtainable.
Follower of the Old Ways is obtained from completing "Zakuulan Devotee" achievement.
Fully Armed and Operational is obtained from completing "All For One" achievement.
Galactic Liberator is obtained from completing "You're All Clear, Kid!" achievement.
Lone Champion is unobtainable.
Master of Mayhem is obtained from completing "Master of Mayhem" achievement.
Physical Backup Unit is obtained from completing "Ghost Mode" achievement.
Simulated Meatbag is obtained from completing "Simulated Meatbag" achievement.
Sprint Champion is obtained from completing "Sprint Champion" achievement.
The Ever-Watchful is obtained from completing "A Shrouded Vigil" achievement.
The Mysterious Stranger is obtained from completing "The Mysterious Stranger" achievement.
The One and Only is obtained from completing "One For All" achievement.
The Unmarred is unobtainable.