While there are many ghosts at Hogwarts, none of them are actively involved in teaching.
* The Nearly Headless Nick: The resident ghost of Gryffindor Tower, he is a friendly presence but doesn't have any teaching duties.
* The Bloody Baron: The ghost of Slytherin House is known for his dark history and keeps to himself, not involved in education.
* The Grey Lady: Hufflepuff's ghost is more of a sad figure and not known for any teaching role.
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