The Machine Empire are a massive race of robotic beings, who are led by the Royal House of Gadgetry.The empire, already rules many galaxies before finally arriving to Earth, and despite their vast army of Cogs, Quadrafighters, and monsters are rebuffed by the Zeo Rangers. The Rangers constantly defeated every monster that King Mondo sent to battle them, finally losing patience and over confident in his abilities Mondo battled the Rangers himself only to fail, being destroyed by the Rangers Super Zeo Megazord.
Without their king, the Empire was ruled by Louie Kaboom, the renegade robot created by the vengeful Lord Zedd, and Rita Repulsa. Louie's time as king was short, due to his lack of leadership, he was quickly overthrown by Mondo's oldest son, Prince Gasket and his wife Princess Archerina.Under their leadership the two led the Empire in an invasion of the ranger's hometown of Angel Grove. But with this invasions failure came the return of King Mondo, forcing the prince and princess to flee or else face his wraith. Unfortunaely for the Empire, the entire royal house was shortly after this destroyed by Lord Zedd, and Rita Repulsa, and without the royal house to lead it the empire stopped their invasion of earth.
The Royal House was ultimately rebuilt, and joined Dark Spectre's United Alliance of Evil. During his attempt to conquer the galaxy, the empire was given the task of of invading 3 key planets, KO-35 the home of the Red Space Ranger, Aquitar home of the Alien Rangers, and the Phantom Ranger's home world. Ultimately succeeding in their conquest most of the empire and the royal house were once again destroyed by Zordon's energy wave.
The remnants of the empire then went into hiding, being significantly weakened, until gathered on Earth's moon by General Venjix, in his attempt to recover Lord Zedd's ultimate war machine Serpentara. What he wasn't expecting was a team of 10 Red Rangers who stood in his way of freeing Serpentara.While the team of Rangers battled the Machine Empire generals, the war machine was ultimately brought up to full power, as Venjix snuck aboard to pilot it towards the Earth. Venjix along with Serpentara was finally destroyed by the Red Wild Force rangers attack, finally ending the Machine Empire forever.