Ectoplasm

• Type: Magical Substance
• Source: Poltergeists, Ghosts (video game)
• Appearance: A viscous, slimy substance; often depicted as translucent or greenish in colour (video game).

Ectoplasm is a supernatural substance associated with non-corporeal or semi-corporeal entities like poltergeists. In the wizarding world, it is the essential matter that composes a poltergeist such as Peeves, giving the chaotic spirit a physical form and allowing it to interact with the material world, such as by carrying objects or causing physical mayhem (Pottermore). While the term is not used in the original seven novels, supplementary materials describe it as the key component of a poltergeist's being. The physical appearance is most clearly defined in video game adaptations, where it is shown as a collectible, slimy green substance left behind by spectral figures.

The primary known manifestation of ectoplasm is Peeves, the resident poltergeist of Hogwarts School of Witchcraft and Wizardry, who is described as being composed of it (Pottermore). His ability to create physical mischief, from dropping water balloons to unscrewing chandeliers, is a direct result of his ectoplasmic nature. In the Harry Potter and the Chamber of Secrets (video game), ectoplasm is a tangible material. It is depicted as a glowing green slime that is dropped by enemy ghosts when they are defeated. It can be collected by Harry Potter and is also shown to be left behind by the ghost Professor Binns when he passes through solid objects, such as the blackboard in his classroom (video game).

• It is important to note that the term ectoplasm does not appear in any of the seven original Harry Potter novels by J.K. Rowling. Its existence in the wizarding world is established through supplementary materials.
• The concept is derived from real-world spiritualism and parapsychology, where ectoplasm is a supposed substance or spiritual energy “excreted” by a physical medium in a trance state.
• The most definitive canonical-adjacent source for its existence is the Pottermore (now Wizarding World) website, which explicitly states that a poltergeist is “an indestructible spirit of chaos… made of ectoplasm.” (Pottermore).
• Its most frequent appearance is in the Harry Potter and the Chamber of Secrets (video game), where it serves as a collectible item for the player.