The known HK (Hunter Killer) droids have stopped being made.  Apparently the newest unit HK-77 was recalled because it was short circuiting whenever it accessed it’s advanced programming on rifles.  After the HK Corporation fixed the faulty programming, it did a full diagnostic’s check on the Droid.  Apparently, the Droid’s were unsafe near children, targeting them for being potential threats.

HK-Series Assassin Droid’s were Assassin droids designed to look and speak like Protocol Droid.  Having the same language function as a Protocol droid, they doubled as such.  The HK Droids took pride in what they did.  Some even developed personalities that were Sociopathic or sadistic.  Others never really thought Independently and were usually just Protocol Droids.

Assassin Droids were made illegal to purchase in large quantities a long time ago.  People looking to buy Assassin droids can still buy them for Personal use, mainly only buying one or two. The HK models are one of the oldest Models still in use, the first called HK-01.

HK-01 was more of a prototype, to see if there were any logistical errors.  There was, HK-01 had developed his own personality and became self aware and tried to start a Droid Rebellion.  He “fixed” droids so that they would attack sentient “meatbags” (the HK’s word for Human or Sentient life) on sight.  The Old Republic put it down, although it lasted for some time.

The next model was was HK-24.  Most of these models were purchased by Adascorp to find and retrieve a man by the name of Gorman Vandrayk (a mechanic on the run with a fugitive) and used for security personnel on the ship Arkanian Legacy.  The HK-24 model seemed to be fine, and only reason it was replaced was for improvements.

The next model was  HK-47.  This model was the most famous model, since it did many things that benefited the galaxy.  This droid was constructed for hunting a certain religious sect that doesn’t exist anymore, it helped protect the Old Republic, but it also tried to take over the Galaxy, starting with Mustafar a few years ago.   HK-47 had a few personality traits and flaws that weren’t common in other HK droids.  He loved to kill, almost to excessive tendencies, The Droid also thought he was vastly superior to all other Droids and all other life forms, and another odd trait that now all HK Units seem to share was his speech.  He would add a label onto all his sentences.  This model was mistaken for a Protocol droid the most, so much in fact that he called his Assassination programs, his “Assassination Protocols” .  This model also described love and some other words falsely, saying that love was shooting someone in the knee caps with a sniper rifle.

The next model was HK-50, the exact thing as HK-47 just more having more programs and a self destruct sequence.  Another HK model was made called the HK-51, nearly identical to HK-50 only more adept at killing members of a certain religious cult
The HK model should have ended exclusively there.  However, HK-47 had survived 3000 years on Mustafar.  He created 3 other Models,  HK-58 Aurek, HK-58 Besh, and HK-77, each one designed to do something else.