Nightmare

Were you looking for
*Emerald Nightmare, the corruption within the Emerald Dream.
*Nightmare (quest), a Twilight Highlands quest.
*Nightmare (warlock talent), a warlock talent.
*Nightmare (pet battle ability), a pet battle ability.
*Nightmares, a story in Legends Volume 5.
*Horses connected with the name nightmare:
**Felsteed
**Dreadsteed
**Warforged Nightmare
**Lucid Nightmare