There are 4 unique codex entries in the Bestiary section on Korriban. 3 are accessible to all Imperial players regardless of class and 1 is class specific.
K'lor'slug is obtained from killing K'lor'slug Broodwatcher. It can also be obtained from killing Agitated K'lor'slug, K'lor'slug Brood Mother, or K'lor'slug Broodmother on Korriban or Ferocious Bogworm on Taris.
Codex type: Bestiary | Faction: Imperial | Class: All
Associated Achievement: Beastmaster of Korriban
Shyrack | Coordinates: -314, 143 | Location: Korriban: Sith Academy: Ritual Chambers
Shyrack (Inquisitor) | Coordinates: 346, -321 | Location: Korriban: Tomb of Marka Ragnos: The Reliquary
Shyrack is obtained from killing Shyrack Mauler during "The Blood Legacy" on a Sith Warrior or Sith Inquisitor or Shyrack Screecher during "A Little Knowledge" as a Sith Inquisitor. Shyrack is unobtainable for Bounty Hunter and Imperial Agent characters.
Codex type: Bestiary | Faction: Imperial | Class: All
Associated Achievement: Beastmaster of Korriban
The Beast of Marka Ragnos (Warrior) is obtained from killing The Beast of Marka Ragnos during "Slaying the Beast" mission.
Codex type: Bestiary | Faction: Imperial | Class: Sith Warrior
Associated Achievement: None
Tuk'ata is obtained from interacting with a Clickable Corpse.
Codex type:Bestiary | Faction: Imperial | Class: All
Associated Achievement: Beastmaster of Korriban