The power to
use the abilities of demons and undead. Combination of Demon Physiology and Undead Physiology. Variation of Hybrid Physiology. Opposite to Angelic-Undead Physiology.
Necrodemon/Necrotic Demon Mimicry/Physiology
User with this ability either is or can transform into a combination of an demon and an undead. Their presence is extremely unnatural and/or corrupt. They specialize in the raw power of unholy and necrotic energies for powerfully destructive effects.
Certain hybrid types may still rely on their undead species need to feed on blood, life-force, flesh, etc.
May be vulnerable to holy powers, artifacts and incantations.
If resurrected, may lose access to undead powers.
May corrupt the user's mind.
Marceline (Adventure Time) is half-demon and half-vampire.
Purgatori (Chaos Comics) is an ancient Egyptian vampire who gained demonic attributes after drinking Lucifer's blood.
After being sent to Hell, Jason Voorhees (Friday the 13th: The Game) escaped, becoming a charred, demon-revenant hybrid in the process.
Jason Voorhees (Friday the 13th) was revived as a Deadite by his mother using the Necronomicon Ex-Mortis...
...with his heart becoming a demonic worm after his body was destroyed.
The Deadites (Evil Dead) are undead beings possessed and reanimated by a demon summoned from the Necronomicon.
Ed (Evil Dead) has become a Deadite.
Hosenki (InuYasha) is an undead oyster demon.
Freddy Krueger (A Nightmare on Elm Street) is the ghost of a child murderer resurrected and empowered by a trio of dream demons.
Tristana Medeiros (Rec) is the first host to a demonic parasite/virus that can reanimate and convert people...
...which was transferred into Ángela Vidal in order to escape its dark prison.
The Stitched (The Stitched) are near indestructible corpses reanimated by demonic magics.
BLU Nnnngh Sniper (TF2 Freak) may be half-zombie, half-demon.
Gasper Vladi (High School DxD) is a dhampir who was reincarnated as a devil by Rias Gremory.