Xylan

The Xylans were an ancient species that built Kalonn, a planet-sized droid, for the sole goal to exterminate all life in the galaxy.

Since Kalonn introducing itself as the "102st Exterminator", The Xylans probably built at least 101 other droids for the same purpose.

Behind the scenes
There is no indications about the era where the Xylans lived. But Kalonn said to have been asleep for "eons".It can be noted that the droid said its mission was to "exterminate all life in this galaxy", so perhaps the Xylans inhabited another.