Since their debut in 1993's Mighty Morphin Power Rangers, the titular Rangers have faced off against a slew of interesting, creative threats. Combining martial arts, monsters, giant robots and science fiction, the series contained everything perfect for the ideal Saturday-morning kids' action series. The various incarnations of the team have cultivated a passionate fan base that goes beyond young viewers, and many of them love to imagine new villains making an entrance.
Source：https://www.cbr.com/power-rangers-other-tv-characters-villains/
