There are 29 unique codex entries in the Achievement: Titles section from Operations. 25 are accessible to all players regardless of class or faction and 4 are unobtainable.
Anomalously Skilled is obtained from killing Lady Dominique during "[OPERATION] The R-4 Anomaly" mission in [VETERAN] difficulty. It can also be obtained from any other boss depending on the order of master achievement completion.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Codebreaker is obtained from interacting with the Elevator during "[OPERATION] The Nature of Progress" mission. Someone in your group must have the Dxun Cipher achievement completed to unlock this.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Conquerer of the Dread Fortress is unobtainable.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Delicious is obtained from killing Delicious Rampaging Charger with the Czerka Sanitizer Droid during "[OPERATION] The Nature of Progress" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Deposer of the Dread Masters is unobtainable.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Destruction Incarnate is obtained from killing IZAX during "[OPERATION] Gods from the Machine" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Dragonslayer is obtained from killing Dread Master Styrak during "[OPERATION] Scum and Villainy" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Dread Master is obtained from killing the Dread Council during "[OPERATION] The Dread Palace" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Dread Slayer is obtained from killing Dreadful Entity during "[OPERATION] Terror From Beyond" mission in [VETERAN] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
from Beyond is obtained from killing Terror from Beyond during "[OPERATION] Terror From Beyond" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Gate Crasher is obtained from killing Dread Master Brontes during "[OPERATION] The Dread Fortress" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Minesweeper is obtained from killing Colonel Vorgath during "[OPERATION] Explosive Conflict" mission after defusing a mine.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
of the Ruined World is obtained from killing Colossal Monolith during "[OPERATION] Colossal Monolith" mission in [VETERAN] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Slayed the Replicator is obtained from killing Propagator Core XR-53 during "[OPERATION] Relentless Replication" mission.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Slayer of the Machine Gods is obtained from killing IZAX during "[OPERATION] Gods from the Machine" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Apex Predator is obtained from killing Apex Vanguard during "[OPERATION] The Nature of Progress" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Dxun Reaper is obtained from killing Apex Vanguard during "[OPERATION] The Nature of Progress" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Eternal Warrior is obtained from killing Hateful Entity during "[OPERATION] Scum and Villainy" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Fearless is obtained from killing IZAX during "[OPS] Descent into the Dark Fortress" mission as an Imperial player or "[OPS] The Bastion of Fear" mission as a Republic Player.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Furious is obtained from killing Golden Fury during "[OPERATION] Toborro's Courtyard" mission in [VETERAN] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Infernal is unobtainable.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Revanchist is obtained from killing Revan during "[OPERATION] Temple of Sacrifice" mission in [VETERAN] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Transcended is obtained from killing Ultimate Hunter during "[OPERATION] The Nature of Progress" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the True Anomaly is obtained from killing Lady Dominique during "[OPERATION] The R-4 Anomaly" mission in [VETERAN] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the True Apex Predator is obtained from killing Apex Vanguard during "[OPERATION] The Nature of Progress" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
the Unyielding is unobtainable.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Ultimate Hunter is obtained from killing Apex Vanguard during "[OPERATION] The Nature of Progress" mission in [MASTER] difficulty. It can also be obtained from any other boss depending on the order of master achievement completion.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Unseen Assailant is obtained from killing The Eyeless during "[OPERATION] The Rakghoul Nightmare" mission.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None
Warstalker is obtained from killing Warlord Kephess during "[OPERATION] Explosive Conflict" mission in [MASTER] difficulty.
Codex type: Achievement: Titles | Faction: Both | Class: All
Associated Achievement: None