Just out of pure curiosity, what is the Catholic Church's position on the existence and experience of ghosts?
Generally, ghosts are found in pre-Christian mythologies, but they're powerful ideas that persisted in the popular imagination, along with fairies and centaurs and winning the lottery. You're not going to find anything in the Bible that has much of a direct correlation (other than maybe 1 Samuel 28:3-25) to what we would associate with ghost stories.
The Bible (and Catholic tradition) talk about two types of spiritual created beings: angels and human beings. The angels chose to be either faithful to God (the good angels) or to reject him (the demons). God can permit both types of angels to be active on earth: think of your guardian angel (Matthew 18:10, Acts 12:15) or of demonic activity (of all types, including even manifestations through ouija boards and other occult objects).
The tradition of the Church talks about visions that saints have had of other saints in Heaven (St. John Bosco's dream in which St. Dominic Savio spoke to him, for instance), of saints who saw souls in Purgatory manifesting themselves on earth (St. Padre Pio tells a rather chilling story), and some saints have had visions of Hell though I can't think of any who have spoken with souls in Hell (something like Luke 16:19-31 or Dante's Inferno).
But ghosts wouldn't be some sort of third "type" of creature. Nor should we associate them with some category of angel or humans in the afterlife; it's the opposite instead: Manifestations of spiritual realities that we're not sure how to categorize can end up being called "ghosts."
Still, all in all, the fact of the matter is that it's far more common that "ghost stories" be just stories, or manifestations of some far more mundane physical reality rather than something truly hair-raising.
God bless you!
- Father Shane