Undead are once-living creatures brought to a horrifying state of undeath through the practice of necromantic magic or some unholy curse.

Are undead creatures?

The undead are beings in mythology, legend, or fiction that are deceased but behave as if they were alive. ... The undead may be incorporeal (ghosts) or corporeal (mummies, vampires and zombies). The undead are featured in the belief systems of most cultures, and appear in many works of fantasy and horror fiction.

Is undead a creature DND?

Undead were once-living creatures that had been animated by spiritual or supernatural forces.