There is no official weakness for Michael Myers in the Halloween universe. However, fans have come up with different possibilities. One theory is that Michaels obsession with Halloween could be a weakness, as he only kills on or around October 31. Another theory is that his obsession with his targets, namely Laurie and Jamie Lloyd, could be a weakness. Some viewers have also pointed out that Michaels iconic mask could be a weakness, as every time he has been unmasked, he stops killing, even though he had his victim in front of him and completely helpless. However, it is important to note that these are just fan theories and not official weaknesses. Michael Myers has survived all types of improbable situations throughout the Halloween franchise, making him seem like an indestructible force.