Holy Ghost

The Holy Ghost is one of God's three people persons, that God is, which they all are... you gotta squint and hold it back a little to see it. Anyway, the Holy Ghost is one of the last known ghosts to survive the Middle Ages, owing to its captivating "holiness" which helps with attachment to the human endocrine system.

However if you are a Satanic terrorist Muslim, verses promising the Spirit of Truth and whatnot, are referring to Mohammad, not God's Ghost person.