There is one epic enemy on Ziost. It does not grant a codex entry, nor is it required for any current achievements.
The Worldbreaker Monlith world boss.
Codex type: Achievement: Epic Enemies
Codex location: Ziost
Codex coordinates: 637, -166
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: Dark vs. Light: Giantkiller