Question: who are the hogwarts house ghosts?
Answer: Nearly Headless Nick – the Gryffindor house ghost who is nearly headless because he still has his head. ... 
The Bloody Baron – the Slytherin house ghost. ... 
The Grey Lady – the Ravenclaw house ghost. ... 
The Fat Friar – the Hufflepuff house ghost. ... 
Professor Binns – the History of Magic professor at Hogwarts.