Nightmare (eNeMeE in the English dub of the anime) is a wicked final boss character and major character in the Kirby series, despite only making three major appearances in the games. His goal is to spread dark nightmares and influences throughout the galaxy, and uses his cunning wit to accomplish the feat.

In his debut, Nightmare is responsible for corrupting the Fountain of Dreams and attempting to spread his nightmares all across Dream Land. King Dedede tries to stop Nightmare from succeeding by breaking the Star Rod, but Kirby unwittingly summons Nightmare when he returns the Rod to the tainted Fountain, and has to defeat Nightmare before his evil plans become reality.

Nightmare first rose to prominence in Kirby: Right Back at Ya!, securing the role of the show's main antagonist. He acts clandestinely behind the scenes through his company, Nightmare Enterprises, to attempt to take over Planet Popstar and conquer the known universe.

Nightmare has had notable appearances in Kirby's Adventure, its remake, and Kirby Mass Attack, and has been featured in a number of cameos in other games.