An alien NPC race from the Star Frontiers RPG, described in Zebulon's Guide to Frontier Space. Mechanons are robotic artificial intelligences that have learned to design and mass-produce more advanced versions of themselves, essentially gaining both evolution and reproduction. Originally descended from Eorna robots on Volturnus, they have since rebelled from their former masters and have colonized several other planets, most notably Mechan, a hostile world whose atmosphere is toxic to most forms of biological life.
While the early Mechanons were more like Daleks in their hatred of organic life, later generations (especially those who fought on the UPF side in the Second Sathar War) have been less xenophobic. They are currently petitioning for full UPF membership.
The Guide states that they are an NPC race, since they are a munchkin's dream (built-in weaponry, don't require air/food/water, resistance to the elements, and so on). Doesn't stop the little buggers from begging, though.