Aglæca, also known as the Trench Horse, Cheval de Tranchée, or Grabenpferd, is a name for a humanoid horse-like creature purported to live in the French countryside.

They have a tendency to hide in abandoned trenches, but otherwise they wander the fields, seeking stray soldiers to prey on. They switch between being a biped and a quadruped, but there have been more sightings of them as a quadruped. It is speculated they tend to travel long distances in this form. All sightings report Aglæca to be coughing up blood and pus, as well scratching the blisters covering their body. While they are mute, numerous stories state they strictly communicate via telepathy. It is said their voice sounds glitchy and horrid. They have been reported humming wartime songs in multiple accounts, "The Trail That Leads to Home" being the most common one.

Legend goes they were a young, patriotic British soldier in a cavalry unit who perished early in World War One. He was subjected to a gas attack while trapped in the bowels of a bunker in the trenches. The young man had reached for safety too late, and suffered a horrible fate. Now not entirely alive or dead, they have since transformed into a strange, black, horse-like creature who hides behind a gas mask.

Trivia

• They are based on a Thoroughbred horse, a type of horse commonly used in British cavalry at the time.