Antasma

Antasma is the (supposed) primary antagonist in the upcoming game Mario & Luigi: Dream Team. He is a being who destroyed the Darkstone in order to create chunks that froze the Pi'llows. It's not yet known why he did this. Mario and Luigi are tasked with rescuing the Pi'illows which Antasma froze. His appearance gives the impression of it as a nightmare which the Pi'illows fear.

Trivia

 * Antasma seems to bear similarities in appearance to all of the previous antagonists in the Mario and Luigi series. (Cackletta, Elder Princess Shroob, and the Dark Star.)
 * Antasma's name is likely derived from the Greek word φάντασμα (phantasma), meaning "phantom," "apparition," or "ghost."
 * Antasma can apparently turn into a bat, as shown by the cover for the game. This ability is similar to one of Cackletta's attacks.