Pralor

From Memory Alpha, the free Star Trek reference

A race of beings who used to exist in the Delta Quadrant.

The Pralor were a race of humanoids, who at some point were at war with the Cravic. The two sides constructed Automated Personnel Units to help fight the war. Some point later, truce and peace was declared between the Pralor and Cravic, and the two sides agreed to dismantle the Units, who were constructed only to fight this war. The Automated Personnel Units (such as 3947) couldn't accept this threat to their survival, and turned on their builders, wiping out the entire race - the Cravic counterparts did the same. Both sets of robots continued to fight this war at least up to 2372, when the crew of the USS Voyager encountered them. (VOY: "Prototype").