Derro (originally DERO, Detrimental Energy Robots) have been invented by certain Richard Shaver, in a book titled "I remember Lemuria"
http://www.sacred-texts.com/ufo/irl/index.htm#contents
http://www.sacred-texts.com/ufo/irl/irl04.htm#fn_16
http://www.sacred-texts.com/ufo/irl/irl10.htm
In D&D terms, they could be said to be a human race mutated by a long exposition to negative energy. The above-mentioned author (who seems a bit mad) named them "robots" because they lack free will and are fully under control of an impulse to kill all other living creatures. He also thought that they still live in tunnels under Earth and use mind-control machines on people, which is the reason for mental sickness.
http://www.sacred-texts.com/ufo/irl/index.htm#contents
http://www.sacred-texts.com/ufo/irl/irl04.htm#fn_16
http://www.sacred-texts.com/ufo/irl/irl10.htm
In D&D terms, they could be said to be a human race mutated by a long exposition to negative energy. The above-mentioned author (who seems a bit mad) named them "robots" because they lack free will and are fully under control of an impulse to kill all other living creatures. He also thought that they still live in tunnels under Earth and use mind-control machines on people, which is the reason for mental sickness.