The Pylon Guardian was a type of battle droid created by the Gray Secant, a Gree research starship, for the purpose of guarding the research pylons that the Gray Secant would use to test sentient lifeforms. The large, three-legged droid came in two identical variations—Mk-II and the more powerful Mk-IV—and all Pylon Guardians were equipped with Gree disintegrators, a digital stasis field, and a phase pulse.