Screamy is one of Luigi's Partners, this one of an unknown species, who first appeared in Paper Mario: The Thousand-Year Door. It is unknown why Screamy joined Luigi and pals on his quest, but he did state that he had to "deliver something", though no one knows what he was supposed to deliver and why. These facts make Screamy a very mysterious and unknown character. It is speculated that he is a ghost, considering his name. It is also thought that he is a blob of whipped cream, considering Luigi's story's food theme and the swirl atop his head.
In the upcoming game, Screamy returns as a quite strong character with impressive attacks, such as the ability to turn invisible and the control of weather and lightning. Though his species and origin are still unknown, the game may give him a backstory...
On a dark spooky night in Paper Luigi: The Thousand-Year Compass, Luigi met Screamy, a strange, ghost-based blob of whipped cream in Rapturous Ruins. He followed Luigi, because he had to deliver something, and thought the compass might show him the way.