The Machine Empire is a group of robotic villains in the Power Rangers universe, who first appeared in the television show Power Rangers Zeo and were later mentioned in Power Rangers in Space and Power Rangers Wild Force.
The Machine Empire was a massive alien race and galactic empire of mechanical beings, led by the Royal House of Gadgetry. Possessing countless Cogs, Quadra Fighters, and monsters, the Machine Empire had already conquered an entire chain of galaxies before reaching Earth. It was when the Empire arrived on Earth that they finally encountered a foe capable of repelling their forces, the Zeo Rangers. Numerous monsters from the Empire perished at the Rangers' hands before King Mondo himself took to the battlefield and was destroyed by the Super Zeo Megazord.
It was during Mondo's absence that the Empire was led by Louie Kaboom, a renegade robot created by Lord Zedd and Rita Repulsa, King Mondo's bitter rivals seeking to reclaim their evil empire. He meant well and succeeded in taking over the Machine Empire by exiling Queen Machina and Prince Sprocket. However, Louie squandered their forces and was eventually overthrown by Mondo and Machina's eldest son, Prince Gasket, and his wife, Archerina. The two led the Machine Empire against the Zeo Rangers rather well, initiating a massive, all-out invasion on Angel Grove. Gasket and Archerina came close to beating the Rangers a few times, but were consistently interfered by both the Rangers and one time by Lord Zedd(whom the latter realized that if Gasket succeeded in defeating the Rangers, the Machine Empire would take over Earth and leave both him and Rita in exile). After this invasion failed, King Mondo returned, causing Gasket and Archerina to flee. When the Royal House of Gadgetry were later destroyed by Rita and Zedd, the Machine Empire went into a period of inactivity, useless without the Royal House to lead it.