Targetmaster technology is a technology introduced introduced in season 4 of the The Transformers television series. It is the second such example Binary Bonding, whereby a smaller being (a Targetmaster partner) could transform into the weapon of head of a Transformer (a Targetmaster). It was invented by the Decepticons and The Hive shortly after the invention of Headmaster technology by the Autobots. Later, some Autobots also became Targetmasters.
By the Fourth Cybertronian Civil War, robots that could transform into firearms and other hand-held weapons were not unheard of, one of which was a Decepticon leader and another was fighting in the same war that Targetmaster technology was invented in. However, they were not referred to as Targetmaster partners and those that used them were not Targetmasters. As of now, both Autobots and Decepticons have had Targetmasters and their Targetmaster partners have all been Nebulan.
When the Hive demanded that the Decepticons who had landed on Nebulos to become Headmasters, some Decepticons refused. Cyclonus bargained with the Hive and agreed that only the Decepticons with animal alternate modes would become the Headmasters whereas the rest would have Hive members become their weapons. Zarak liked the idea of a Hive member becoming a powerful weapon and agreed to the plan.
During another clash with the Autobots on Nebulos, the Autobots that the Decepticons took as prisoners were freed and they later became Targetmasters with the remaining resistance members as their Targetmaster partners.