There are 8 unique codex entries in the Achievement: Titles section on Tython. They are class specific.
NAME is obtained from interacting with the Holo-archive Terminal during "Vivicar Awaits" mission.
Codex type: Achievement: Titles | Faction: Republic | Class: Jedi Consular
Associated Achievement: None
Hero of Tython is obtained from interacting with the Jedi Council Chambers during "Fate of the Jedi" mission.
Codex type: Achievement: Titles | Faction: Republic | Class: Jedi Knight
Associated Achievement: None
Jedi is obtained from interacting with the Jedi Council Chambers during "The Forge" mission.
Codex type: Achievement: Titles | Faction: Republic | Class: Jedi Consular
Associated Achievement: None
Knight of the Republic is obtained from interacting with the Jedi Council Chambers during "Weapon of the Jedi" mission.
Codex type: Achievement: Titles | Faction: Republic | Class: Jedi Knight
Associated Achievement: None
Padawan (Consular) | Coordinates: -330, -565 | Location: Tython: Jedi Temple
Padawan (Knight) | Coordinates: -423, -330 | Location: Tython: Jedi Temple
Padawan is obtained from speaking with Master Yuon Par during "The Path of a Jedi" mission as a Jedi Consular player or Master Satele Shan during "Attack of the Flesh Raiders" mission as a Jedi Knight player.
Codex type: Achievement: Titles | Faction: Republic | Class: Jedi Consular & Jedi Knight
Associated Achievement: None
The Indomitable is obtained from interacting with the Jedi Council Chambers during "An Unthinkable Alliance" mission. It is obtained with the The Emperor's Plan (Knight) codex.
Codex type: Achievement: Titles | Faction: Republic | Class: Jedi Knight
Associated Achievement: None
the Keeper of Truth is obtained from interacting with the Ancient Computer during "[HEROIC 2+] The Chamber of Speech" mission. It is obtained with the Zabrak codex.
Codex type: Achievement: Titles | Faction: Republic | Class: Class
Associated Achievement: None