Negator

The Negators are a newly discovered species, apparently antagonistic towards the Scourge and the Nephilim.

Xenobiology
Much of Negator biology is unknown, but they appear to be a type of colony race, formed from clusters of billions of intelligent (the degree of individual intelligence is unclear), multi-purpose single-celled organisms. It is believed that all Negator vessels are formed from these cell colonies (in a manner analogous to coral), with cell groupings taking on specific tasks within the vessel in order to act as pseudo-subsystems.

In this sense, the Negator race is indistinguishable from their ships or indeed any other technology. The origin of the Negators, and the evolutionary conditions that drove them into space, remain completely unknown.