The Void

The Void is an interdimensional rift in the game Super Paper Mario. Its purpose is to increasingly grow in size before it starts to consume and destroy "all worlds". The Void was caused by the bringing of the Chaos Heart, which was created by Count Bleck after marrying Bowser to Princess Peach. According to Merlon the center of The Void is where Castle Bleck is situated, or at least an area similar to such.

The Void appears as an ominous, pulsing black hole that hovers in the skies above. Its size varies depending on the dimension one is in, as each dimension is a different distance from The Void. Frequent waves of tremors indicate that The Void is becoming large enough to be destructive. When The Void finally becomes large and close enough to destroy, the tremors become earth-shattering, space begins to warp and flashes of light consume all matter, leaving behind a stark, white realm of nothingness. The purple Pure Heart was sucked through The Void with Sammer's Kingdom, and was turned to stone in the World of Nothing that remained; ultimately, Queen Jaydes of The Underwhere, with her "power over life and death", was able to restore the heart.

The dimensions to be utterly obliterated by The Void were Sammer's Kingdom, Land of the Cragnons, Flopside and Yold Town while Flipside, Lineland, The Bitlands and Castle Bleck only became dangerously close to destruction. The Void was closed after the Chaos Heart was destroyed by the Pure Hearts brought forward when Count Bleck and Tippi married, and the destroyed areas were restored as a result.

Trivia

 * Although The Void is always referred to as "The Void" (with a capital "the") in-game regardless of position in sentences, Count Bleck calls the dark hole "the Void" in Nintendo's Super Paper Mario website.
 * The Void could be seen in the Overthere, indicating that it was going to destroy the aftergame as well. What would have happened to the victims of The Void, or any characters who died in general had this dimension been destroyed is unknown. The Void could not be seen in The Underwhere, though, implying that The Void's victims might be sent there (since it is one of the most unpleasant worlds a person could be sent to). However, it is also likely that the Void couldn't be seen in the Underwhere due to fact that the Underwhere is underneath the Overthere, and thus underground. Additionally, it is mentioned a few times by various Shaydes that the Underwhere is not so unpleasant and it is implied there is a worse place below the Underwhere, where Bonechill was imprisoned. Also, The Void is supposed to destroy everything, so there is no reason why it would spare a single dimension or place. Instead, it is likely that the places would have been completely erased, like Sammer's Kingdom, leaving only empty space.
 * In Flipside and Flopside, before Chapter 8 and after Chapter 7, almost everyone talks about The Void, but after Chapter 8, almost no one mentions it, even though the Flopside residents died.