Shadow Droids were Imperial starfighters whose pilots were organic brains that had been surgically implanted. This made the Shadow Droid more of a cyborg than an actual battle droid.
The cybernetic hardware that the brains were integrated into deprived the pilots of any remaining Humanity, but it amplified their reflexes and abilities to a degree they could never have achieved otherwise. As a final gift, Emperor Palpatine granted these creations the capacity to tap into the dark side, effectively turning them into extensions of his own will.
The Shadow Droid was a sleek starfighter capable of matching the speed of the New Republic's X-wing in space. Within a planet's atmosphere, they employed a highly maneuverable repulsorlift system, and they could achieve supersonic speeds with brief bursts from their ion engines. Furthermore, these droids were coated in a shiny black alloy that made them difficult to detect on sensor readings. Twin wings extended from the control pad supported repeating blasters, ion cannons, and electromagnetic pulse guns. The droids also featured two additional pylons used as racks and launchers for proton torpedoes and concussion missiles. Two smaller dorsal lasers covered the rear field of fire, and a long-range antenna enabled the fighters to transmit a dense binary code stream between themselves and their command ship.
The shadow droid project, spearheaded by Umak Leth, represented one of the most sinister endeavors undertaken by the Empire. Their biotic nature gave them advantages beyond the capabilities of automatons. These refined fighters wielded the power of the dark side of the Force. Emperor Palpatine's experiments were essential to the creation of the Shadow Droids, and following the defeat of the First Galactic Empire at Endor, Palpatine's spirit took residence in a new clone body and initiated fresh strategies for military domination. The research for the Shadow Droids originated on Byss, the Emperor's throne world, and later expanded to various think-tanks and manufacturing centers hidden on secluded worlds within the Deep Core.
The deadly machines were more cyborg than droid because they had the brains of fatally wounded TIE fighter ace pilots implanted into them, and they could manipulate the dark side of the Force. The initial conception of Shadow Droids occurred on the resurrected Emperor Palpatine's throne world of Byss. As manufacturing was secretly accelerated, the evil machines were also produced on other Deep Core worlds.
The method by which these droids gained access to and manipulated the dark side of the Force remains unclear, but it is highly probable that they used it as a sixth sense to identify potential threats. The Galactic Empire deployed Shadow Droids during the Battle of Balmorra and to defend Palpatine's flagship Eclipse II near Onderon.