Cocytus

Cocytus is the Floor Guardian of the 5th Floor in the Great Tomb of Nazarick in the anime Overlord. He is a powerful level 100 NPC created by the Supreme Being Warrior Takemikazuchi.

He has a massive, imposing insectoid appearance — a 2.5-meter-tall bipedal fusion of a mantis and an ant, complete with four arms, a long tail, sharp icicle-like spikes covering his body, a powerful jaw, and pale blue icy armor that gives off a freezing aura (earning him titles like "Ruler of the Frozen Glacier").

Cocytus is a pure warrior at heart, deeply honorable, respects strong opponents and the spirit of combat (often with a samurai-like code), and speaks in a very formal, archaic manner. He wields multiple weapons expertly (especially blades) across his four arms and commands insect-type minions on his frozen floor.

He's fiercely loyal to Ainz Ooal Gown and serves as one of Nazarick's top melee fighters.