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 "102nd Exterminator", the Xylans presumably built at least 101 other droids for the same purpose.

Text and facts from the “Xylan” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.