The Slaver Empire was a political entity extant in the Milky Way Galaxy one billion years prior to the 23rd century. They were said to be the masters of all intelligent life in the galaxy. After they and their subjects were annihilated during a cataclysm, intelligent life had to evolve all over again. (TAS: "The Slaver Weapon")
At one point, historians theorized that the Guardian of Forever might have been an artifact of the Slaver Empire, but the Guardian was found to predate the Slavers. (Federation News Service 2:1: "Multi-'Dimensional' Technology")
Among the artifacts from the Slaver Empire were devices known as stasis boxes. The Romulan cloaking device may have been based on Slaver Empire technology found in one such box. (Star Trek: Shadowstar Station: "Hegemony")
- This article refrains from referring to any information from Larry Niven's non-Trek work or the Man-Kzin Wars novels. The Slaver Empire in the Trek universe(s) may be different in details from that of Larry Niven's Known Space series, similar to how Kzin in Trek are "kinder and gentler" than those in Known Space.