The "Machine Empire" refers to a fictional group of robotic villains from the Power Rangers franchise, particularly featured in the Mighty Morphin Power Rangers series. This empire is characterized by its advanced technology and mechanical soldiers, often seeking to conquer Earth and defeat the Power Rangers. Led by the villainous Lord Zedd, the Machine Empire employs various robotic creatures and machines to carry out its plans. The group represents a significant threat to the Power Rangers, showcasing themes of technology versus nature and the struggle between good and evil in the series.