Hamusuke

ハムスケ

Hamsuke resembles a giant Djungarian hamster with a long snake tail. Six sigils dot her silvery fur.

Before being inducted in the Great Tomb of Nazarick, Hamusuke was very boastful and prideful of her ability and power as the "Virtuous King of the Forest." However, since meeting Momonga and witnessing the power of the denizens of Nazarick, she has seen how vastly inferior she is. She accepts this and swears loyalty to Momonga, willing to do anything to please his master and earn his keep.

(Source: Overlord Wiki)