HK-24

Originally built by Czerka Corporation to be sold in large quantities to the Galactic Republic and Planetary governments during the Mandolorian Wars but after being met with little success the production of such droids stopped and the factories were closed and abandoned.
 
The legacy of the HK-24 lived on when the Sith Lord Darth Revan used schematics of the droid to construct his personal assassin droid, HK-47.