For a festive religious holiday centered around love and family, Christmas sure does have a lot of monsters. People just love the thrill of horror tales. From Wales, we have the tradition of Mari Lwyd, which is a variation on wassailing or caroling. Imagine a shrouded horse skull knocking on your door, demanding to be let in! But where did this custom come from, and what does it mean? Scholars disagree on its origins, and written records from Welsh history don't tell us much. Was it a secret that no one was supposed to disclose, or just so common that no one thought about it much? In this episode of Monstrum, we learn what we know and what we don't know about Mari Lwyd, including how to pronounce it. While we may not have documentation of its origins, the photographs from the 19th and 20th centuries are pretty frightful. They end the video with a look at how so many scary dark characters, meaning monsters, pop up in our Christmas traditions. The last minute of the video is an ad.