Jesus vs. Frosty (a.k.a. The Spirit of Christmas), 1992.
Written, Directed, Produced, Animated and Voiced by Trey Parker and Matt Stone.
An early precursor to South Park, Trey Parker and Matt Stone created the four minute short The Spirit of Christmas as students as the University of Colorado. Animated by hand using construction paper, glue and an 8mm camera and featuring characters not dissimilar to their South Park counterparts, The Spirit of Christmas is the first of two shorts produced by the pair under the same title (the other coming in 1995) and has come to be known as Jesus vs. Frosty.
After building a snowman, four young boys put a magic hat on their creation which brings it to life as an evil version of Frosty the Snowman. It quickly kills the only named character, Kenny (who happens to resemble Cartman), leading to the phrase “Oh my God! Frosty killed Kenny!”, and pursues the children until they stumble across a nativity scene, with the baby Jesus coming to their rescue and defeating the creature.
The Spirit of Christmas premiered at a student film screening in 1992 and led to Fox executive Brian Graden commissioning a follow-up, Jesus vs. Santa, in 1995.