Karl Knave is the main antagonist of the Goosebumps three-part episode, Chillogy.
Karl is the sinister mayor of a miniature model town called Karlsville. He transports children into his town where he torments them and/or attempts to kill them.
In Part I: Squeal of Fortune, Karl sucks in Jessica, a con-artist, and convinces her to sell his lemonade on a hot day. He takes advantage of her greed and tricks her into raising prices. When she is exposed, Karl transforms her into a pig and sends an angry mob after to cook her for him. She narrowly escapes Karlsville.
In Part II: Strike Three... You're Doomed! he sucks in Matthew, who wants to be a professional baseball player. Karl puts Matthew in a lethal baseball game run by monsters and killer baseballs, with obstacles such as lava pits. Matthew also manages to escape and he and Jessica try to find a way to destroy Karlsville. However, Matthew's little brother Todd gets lured into Karlsville by a mail scam.
In Part III: Escape from Karlsville, he attempts to turn Todd into plastic while still conscious. Todd asks why he's doing this and Karl responds that it's his hobby. He delays the process to torment Todd and enjoy his fear. Matthew and Jessica arrive and save Todd. The three escape Karlsville when Matthew's mother unwittingly vaccums up the citizens of Karlsville. The kids later burn all the houses and buildings of Karlsville in the fireplace to be sure they're rid of Karl. However, it turns out Karl survives the vacuum and escapes, ready to continue his rampage.
- Karl was played by Daniel Kash.
- Karl is not based on any villain from the the Goosebumps books because Chillogy is an originial story of the TV series.