HK-51 series assassin droid

"Revelation: We have already begun construction on a new generation of HK units. When the last of our deficiencies are accounted for and corrected, they shall be the most formbidable assassination droids in the galaxy."

- An HK-50 assassination droid

HK-51 assassin droids were advanced versions of HK-50 assassin droids that were manufactured by G0-T0 in the HK Manufacturing Plant. Their appearance was like that of HK-47 and the HK-50's save for their photoreceptors glowing icy blue instead of heated orange and their durasteel was black in color.

Characteristics
"Schematics for HK generation 51: Blaster to accuracy ratio: increased by 21%. Durasteel impact frame resistance: increased. Conclusion: halting production. Units are in standby mode, pending further testing of behavior cores and assassination protocols."

- Log of the HK-51's development status

Behind the scenes
In a removed part of Star Wars: Knights of the Old Republic II: The Sith Lords, HK-47 would confront G0-T0 on Malachor V, and a group of HK-51 droids would come and help him defeat G0-T0, if HK-47 had programmed them to aid him while in the HK Manufacturing Plant (HK-47 could also choose to destroy them, causing him to lose to G0-T0). The HK Manufacturing Plant was also a removed part of the game.

Appearances

 * Star Wars: Knights of the Old Republic II: The Sith Lords