to me people who have met an untimely end (murdered mainly) like moaning murtle was killed by the basali thing (big snake) SHES A GHOST
nearly head-less nick had his head damaged brutally. hes a ghost
and many of the others meet there death in siilar circumstances
but why they are at hogwarts i dont know but we dont know if cedric is a ghos yet as he was murdered by voldy ... and we didnt really see that much of hogwarts in the last book so he mite be plus his parents still could be they are still quite recent deaths unlike the others... and theres still 2 books for them to show up ..
Originally posted by eezy45
well, didn't nearly headless nick say that being a ghost or not is a choice you can make when you died?and that it would be nicer for a dead's soul to stay in.. heaven?
and that's why they're so rare... he did explain that to harry didn't he
that he definitly did....becuz harry wanted to know if sirius would come back as a ghost