Why I'm just trying to spread a little Yuletide fear!
~ Santa Clause
Santa Claus is the famous Anthropomorphic Personification of belowed holiday as we know it. But how about if an incarnation of Santa Claus is portrayed not as fatherly figure but instead as a villain or worse, a figure of nightmare?
Bad Santa is the villainous portrayal of either Santa himself, a malevolent being that associated with him (such as a Krampus), or a villain whom dressed like Santa. For the first two cases, those Bad Santas would perform similar job with more benevolent, ordinary Santas but in twisted and villainous ways. These Santas of course, would inspire nothing but fear and terror to children and adults alike, where the impact also affect their innocence.
~ Billy Chapman's infamous catchphrase.
Christmas can sure can the Dickens out of people
~ Santa Clause while looking a a book of "A Christmas Carol".
"The Krampus", a trope based on a concept of the mythical fiend often confused with this term.
An extreme form of Paranoia Fuel. Named after the movie of the same name. If it is the real deal, it is a case of Adaptational Villainy. If not, it usually ends up fighting the real deal, "Badass Santa".