What cinematic universe includes the characters Freddy Krueger, Jason Voorhees and Michael Myers?

Although Freddy Krueger ('A Nightmare on Elm Street'), Jason Voorhees ('Friday the 13th') and Michael Myers ('Halloween') are three of the most iconic killers in horror movies, they belong to separate franchises. Freddy and Jason did share the screen in 'Freddy vs. Jason' (2003), but Michael Myers has never appeared in a crossover with them, remaining in his own cinematic universe.