Technobeasts were part machine, part organic Sithspawn mutants. They were created by infecting living organisms with the nanogene spore, a technovirus developed through a combination of Sith alchemy and a Force technique called mechu-deru. The virus grew metallic tumors over the bodies of its victims, ultimately lobotomizing their brains and transforming them into weaponized cyborgs. Living subjects from a number of different species were infected by the virus, spawning mutated amalgamations of metal and flesh in a variety of shapes and sizes.
In the last quarter of the New Sith Wars, a Dark Lord of the Sith known as Belia Darzu devised a dark side ritual called mechu-deru vitae, using it to build her own army of technobeasts—the Metanecrons. Housing the creatures inside a hidden stronghold on the planet Tython, Lord Darzu used her army of mutated cyborgs against the Galactic Republic and the Jedi during the two-decade Sictis Wars. The subsequent assassination of Darzu ended the creation of new Sithspawn hybrids, leading to their disuse after the conclusion of the New Sith Wars.
The technobeasts were first mentioned unnamed in Tales of the Jedi Companion, a roleplaying supplement published by West End Games in 1996. The creatures received yet another unidentified reference in The Lost Art, an adventure seed featured in the 2001 article entitled The Emperor’s Pawns. In 2005, both of these references were retconned by Abel G. Peña, an author who named the creatures in a Hyperspace fan club article called Droids, Technology and the Force. The New Essential Guide to Droids provided more detailed information regarding the technobeasts in 2006, along with the first images of the creatures, by artist Ian Fullwood. The technobeasts made their debut appearance in Darth Bane: Rule of Two, the second novel of Drew Karpyshyn‘s Darth Bane Trilogy. The Junk Golem figurine included in The Force Unleashedminiatures set was once called a «technobeast.» In the third part of The Imperial Warlords: Despoilers of an Empire, the alchemical creations of a character named Cronal were also dubbed «Trailian technobeasts.»