Sleepers are a new type of rogue drone NPCs. Introduced with the Apocrypha expansion and found only in the uncharted systems beyong wormholes, the Sleepers, are rumoured to have better anti-player AI strategies, in addition to being more tough and powerful in general.
The Sleepers were masters of virtual reality, neural interfacing and cryotechnology.
Their salvaged and recovered remains and other artifacts allow construction of Tech 3 items.
See also: Sleeper Technology skill