There are two epic enemies on Hoth. The codex entries are not required for any achievements, but the two bosse are.
The Gargath world boss.
Codex type: Achievement: Epic Enemies
Codex location: Hoth: Clabburn Tundra
Codex coordinates: -2132, 449
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: Gargathuan | Hell Hoth No Fury
The Snowblind world boss.
Codex type: Achievement: Epic Enemies
Codex location: Hoth: Glacial Fissure
Codex coordinates: 375, 1050
Faction: Both
Class: Bounty Hunter - Imperial Agent - Jedi Consular - Jedi Knight - Sith Inquisitor - Sith Warrior - Smuggler - Trooper
Associated Achievement: Dark vs. Light: Giantkiller | Hell Hoth No Fury | Whiteout | World Boss Ingredient Sampler
World Boss Ingredient Connoisseur | World Boss Ingredient Enthusiast