Phobetor in bed

Ikelos who was one of the Oneroi was the personifications of nightmares and appeared in various types of dreams.  He made shapes of humans appear in dreams.

Ikelos was a son of Nyx. He resided with his brothers, Morpheus and Phantasos in the Underworld. His appearance was that of a daemon, but he appeared in the form of animals and monsters when entering dreams, most commonly a lion or bear.