Nightmare is a boss from the Japanese-exclusive Ghosts N Goblins sequel, Makaimura for WonderSwan - the fourth game in the series and released solely on the WonderSwan system.

Nightmare itself is based on a legendary creature of the same name, often envisioned as a demonic horse - this particular Nightmare is no exception and attacks Arthur during his quest to defeat the demon lord, Azazel.

Nightmare is a fire-demon, being surrounded by four fireballs which the horse uses to attack via hurling them at Arthur.