Mare

The mare enters the place where a person should feel safest: their bed. In traditional accounts, it presses or rides upon a sleeper, making rest frightening and difficult. Related stories blame such beings for tangled hair and horses found exhausted in the morning. Its form varies; some tales connect the nighttime visitor with a person encountered in daylight.

Collections from Germany, Denmark, and neighboring regions preserve overlapping beliefs about mares, maras, and other oppressive night beings. Some stories describe them entering through tiny openings and becoming trapped when the opening is blocked. The “mare” in “nightmare” refers to this supernatural visitor, rather than a female horse.

The mare lends itself to intimate horror: a familiar bedroom, an unseen weight, and uncertainty about whether the sleeper has awakened. Its ability to cross small openings can make an apparently secure room feel exposed. Tangled hair or an exhausted animal may provide a physical trace by morning.

• D. L. Ashliman, Night-Mares: Legends and Superstitions About the Demons That Cause Nightmares, including translated German and Danish accounts.