Zankou was a powerful Upper-Level-Demon, and one of the deadliest threats the Charmed Ones had ever faced. Malevolent and beyond cunning, Zankou was among one of the strongest demons out there. Capable of killing and absorbing the powers of other demons, he was imprisoned by The Source after attempting to challenge him for the title of ruler of the Underworld.
He was later released out of desperation by demons, in hopes that he would disrupt good magic, and overcome the threat of the avatars. He has helped the Charmed Ones fight against the Avatars, when they mutually realized that the idea of Utopia created by the Avatars would wipe out demons entirely, as well as remove the free will of every other living creature.
After they defeated the Avatars, Zankou went back to his wicked ways and terrorized the Charmed Ones. Zankou continually attempted to steal the Book of Shadows, succeeding once. When he attained the Book of Shadows, he was able to use a potion inside the book to steal Phoebe Halliwell's and Piper Halliwell's powers. When Zankou took in the Nexus, the Charmed Ones banished it with a spell that vanquished Zankou once and for all.
Zankou is an extremely formidable demon with a plethora of abilities. Known powers used by him include:
- Spell Casting
- Super Strength
- Shapeshifting - Absorbed
- Molecular Immobilization/Combustion - Stolen from Piper
- Premonition - Stolen from Phoebe
- Power Absorption
- Particle Swarm
- Flame-Based Teleportation/Teleportation Mimicry