The Xiliens are a sapient species of cybernetic reptilian humanoids who long ago interbred with humanity, causing their species to gain the M-base. They can alter DNA in order to add M-base to other species, which they have the ability to control. They have used not only Earth's own daikaiju against it, but also three extraterrestrial daikaiju: King Ghidorah, Gigan, and Monster X. They naturally have the ability to become Keizers.