Void

''This article describes the realm. Alternatively, you may be looking for the space platform of the same name or map of the same name.'' "I have journeyed through the darkness between the most distant stars. I have beheld the births of negative-suns and borne witness to the entropy of entire realities..."

- Zeratul, possibly giving insight into the nature of the Void.

The Void is a mysterious phenomenon.

Unlike warp space, which is a dimension unto itself, the Void appears to be a manifestation of the material universe – the "cold void of space."

The Dark Templar
The Void is understood by the Dark Templar.

The Void serves two purposes for the Dark Templar. It is from the Void that they draw energy to use psionic powers, as due to severing their nerve-appendages in a display of contempt for the Conclave, they lost the primal link the rest of the protoss share. Although this removed them from the control and discipline the Khala provides, the Void provides the dark templar with psionic powers unheard of by their brethren. In addition, the "currents" of the Void allow FTL travel for the dark templar. These currents are affected by gravity and solar winds.

It appears that the Dark Templar associate the Void with death&mdash;to "embrace the Void" is to embrace death, so to speak. They consider anything that taints the Void to be unholy, and it is a major part of their religion.

Other Races
The Void is inhabited by a mysterious entity at KL-2 calling itself the "Heart of the Void". The KL-2 entity "tainted" the Void, according to the Dark Templar.

The xel'naga understood the Void. Their ships possessed the ability to travel through it. The xel'naga imprisoned the KL-2 entity using the powers of the Void.

It appears that the Overmind knew of the Void in some form or another, as the powers the dark templar wield were similar to its own, such powers being the only thing that could permanently destroy its cerebrates and the Overmind itself.