Black Ship: The Black Ships are the spaceships that tour the Imperium, collecting psykers from planets and returning them to Terra to either be trained or to be soul bound with the Emperor.
Not all passengers survive the journey, as some may already be partially possessed or too weak, but some may be picked for greater things. Inquisitor Draco was spotted as a potential Ordo Malleus Inquisitor on a Black Ship.
Source: Draco by Ian Watson
Submitter: IBBoard
Hive World Terra