Dark Star (Mario)

The dark star was a sentient, evil orb in the game, Mario & Luigi: Bowser's Inside Story. It was a rather large blue orb, with a black star with glowing red eyes on the front. The toads dug up the dark star while building Toadtown., wakening it from a deep sleep. The dark star went on to terrorize the world, until it was finally defeated by the star spirits. The star spirits then sealed the dark star beneath Toadtown in a seal that could only be broken by Princess Peach

Fawful's Plans
After conquering the Mushroom Kingdom, Fawful began to hunger for more power when he heard about the dark star's powers. He kidnapped the pricess and destroied the seal. While the dark star began to awaken, he used its power to create a blockade infront of the castle to prevent anyone from coming, but Mario and Luigi were able to find the three star cures and destroy the blockade.