Christmas traditions have a great many manifestations, and one of the most unusual is a practice from southern Wales surrounding the macabre figure of the Mari Lwyd, which is a horse skull decorated with glass eyes and bows, held up on a pole by a man under a white canvas sheet. (The first photo gives an example, dating from 1904-1910). The Mari Lwyd would visit people’s homes sometime between Christmas and New Year accompanied by a group of men. They would knock on various doors and challenge the dwellers inside to a poetry contest — sort of like a rap battle. (See second image). If the people inside couldn’t respond, the Mari Lwyd would enter with the men and have to be given alcohol.
It sounds creepy and fun and not exactly Christian, but it is difficult to account for where and when the details arose. In fact, the first documentation of a Mari Lywd only goes back to 1800. Many scholars contend that rather than surviving from a pre-Christian practice from the early Middle Ages, it grew out of a European fascination with hobby horses that developed in the 1500-1600s, blending with a trickster tradition of wassailing, which was sort of like a grown-ups version of Trick-or-Treat, but for Christmas. The Welsh “Mari Lwyd” (pronounced “ə vari luid” because, you know, Welsh) usually is thought to mean “Gray Mare” even though some scholars have thought it refers to the Christian figure of Mary.
Anyone who studies European Christmas traditions knows they can get a little creepy, like the demon-figure Krampus that threatens small children. (See the third image for a modern opinion.)
Source(s): “The Mari Lwyd and the Horse Quern: Palimlsests of Ancient Ideas,” Lyle Tompsen (2012), Master’s Thesis, Univ of Wales, Trinity St David. Wikipedia.