The Preservers were an ancient race of aliens known to have existed within the galaxy. They were known for visiting planets and removing specimens and transplanting them to other worlds. The Preservers were a largely unknown civilization. Due to the absence of any reliable data, it was theorized that they deliberately wiped out all traces of themselves. It wasn't even certain if they themselves were humanoid or had chosen to spread that form for some unknown reason. (FASA RPG module: The Orions: Book of Common Knowledge) However, in 2409 it was revealed that they were Humanoid, and that they were the same race as the Progenitors. (STO mission: Cold Storage)