HK-01
this rogue war droid was considered the mastermind behind the Great Droid Revolution, some 5,000 years before the Galactic Civil War. After gaining a measure of independence, HK-01 began secretly reprogramming all manner of automatons. HK-01's goal was to liberate these droids from their sentient masters. Much of this programming was set to activate upon HK-01's command, at which time the droids all rose up against their owners. Across the galaxy, droids suddenly turned violence and unpredictable: once-loyal battle droids began subjugating entire planets in the name of the Great Droid Revolution. Over time, however, HK-01 was unable to continue his programming, and the code it was using eventually allowed the Old Republic and the Jedi Knights to locate its location and shut it down.