There are 3 unique codex entries in the Achievement: Titles section on Hutta. They are all class specific.
Agent is obtained from interacting with the Suite Holoterminal during "Soiree" mission.
Codex type: Achievement: Titles | Faction: Imperial | Class: Imperial Agent
Associated Achievement: None
Hired Gun is obtained from interacting with Nem'ro the Hutt during "Big Chief" mission.
Codex type: Achievement: Titles | Faction: Imperial | Class: Bounty Hunter
Associated Achievement: None
The Heartless is obtained from completing "[HEROIC 2+] Hostage Cleanup Situation" mission.
Codex type: Achievement: Titles | Faction: Imperial | Class: Bounty Hunter & Imperial Agent
Associated Achievement: None