Epiales

In Greek mythology, Epiales (Ancient Greek: Ἠπιάλης, romanized: Epiálēs) was the spirit (daemon) and personification of nightmares. Alternate spellings of the name were Epialos (Ἠπίαλος), Epioles (Ἠπιόλης), Epialtes (Ἐπιάλτης) or Ephialtes (Ἐφιάλτης).