Shadow Demons are like shadows without thickness expanded from the darkness. From an observer's point of view, it was as if something two dimensional had gained a third dimension. They resemble emaciated humanoid figures with bat wings attached to their backs, their fingers ending in sharp claws. Their figures are pitch black, as if created from darkness itself. The only other color were the eyes, a sickly glowing shade of yellow.
Shadow Demons possess a special ability called 'Shadow Warp,' allowing them to transverse at short distance between shadows. As implied by its name, Shadow Demon could morph into shadows, it is a monster that excelled in stealth and relaying information to their masters. As shown with Sebas or Demiurge, a Shadow Demon is also capable of hiding within a person's shadow and leaving it.
- Shadow Demons are used as protection for the NPCs and Ainz every time they are outside the Great Tomb of Nazarick.
- In the Web Novel, Narberal Gamma uses level 30 Shadow Demons to collect information around E-Rantel. When wounded, they spew a thick black fluid as blood.
- One is stationed at Renner Theiere Chardelon Ryle Vaiself's side due to her alliance with the Sorcerer Kingdom.
- Originally, Ainz Ooal Gown had stationed the Shadow Demons at Carne Village, but for the purpose of building a good relationship with them, he had sent Lupusregina Beta instead.