Antasma

Antasma is the supposed primary antagonist in the upcoming game Mario & Luigi: Dream Team. It is a nightmare who apparently destroyed the Darkstone in order to create chunks that froze the Pi'illows. Mario and Luigi are tasked with rescuing the Pi'illows which Antasma froze.

Trivia
Antasma seems to bear similarities in appearance to Cackletta, Elder Princess Shroob, and the Dark Star. Antasma's name is likely derived from the Latin word phantasma, meaning "spectre" or "apparition."