Power Rangers Zeo
King Mondo is the machine king of the Machine Empire, responsible for conquering several galaxies before his arrival on Earth. When Mondo arrived his first act was to drive away Lord Zedd, and Rita Repulsa from the Earth, but on his arrival with his army he soon found his attempts at conquering repeatedly foiled by the new team of Power Rangers, the Zeo Rangers. But this ultimately piqued his interest in Earth, as he had gradually become bored of conquering as their was little resistance in the universe that could repel him.
Mondo's interest quickly grew into hate, as he constantly failed to defeat the Rangers, with his army of Cogs and monsters. Growing tired, and vastly overwhelming the rangers, he soon battled them himself, only to fall to the Super Zeo Megazord in combat. But this wasn't the end of Mondo, who was rebuilt and chased away the usurpers to his thrown Prince Gasket, and Princess Archernia. Before attempting to battle the rangers one more time, only to be destroyed by a bomb from Rita and Zedd.
Power Rangers in Space
With the entire Royal House of Gadgetry destroyed this time, the Machine Empire stopped their invasion of Earth, disappearing back into space. Ultimately the entire Royal House was rebuilt, and joined Dark Specter's United Alliance of Evil, and participated in the conquering of the universe. With the empire sent to conquer three key planets, KO-35 home to the Red & Silver Space Ranger, Aquitar home of the Alien Rangers, and the Phantom Ranger's home planet. All of which they succeeded in conquering only to be destroyed once again, this time by Zordon's energy wave.