There is very little information on Ropers, though what is known is that they exist in both YGGDRASIL and the New World. In addition there is a subspecies known as Herdropers that possess a hive mind.
According to the Narberal Activity Report, a Roper's fluid is some kind of powerful secret drug.
- Ropers are officially introduced in the Light Novels in the Overlord Bonus Volume.
- According to the author, one of the Five Worst is a Roper-type monster.