The 1978 classic Halloween revolutionized horror and spawned a series of sequels that are still running today. Yet after all these years, there still is no true consensus as to what exactly makes the killer, Michael Myers, tick. In Halloween: The Curse of Michael Myers, it was revealed that he was imbued with the "Curse of Thorn," an ancient druid curse... yet whether this should be considered canon is still up for debate.
The deliberate ambiguity that John Carpenter put into the character of Michael Myers has spawned numerous Halloween fan theories. Why is Michael apparently immortal? Why doesn't he speak? Why does he feel a compulsive need to murder people on Halloween night? These theories about the Halloween movies attempt to answer these questions and more. Some of them are frighteningly plausible, while others border on hilarious, but all of them are definitely worth pondering.
In this theory, the name Sam Loomis is more than just an homage to the iconic horror film and a subtle reference to Jamie Lee Curtis's pedigree. Think about it: what would a bereft Sam Loomis do after failing to save his girlfriend in Psycho? Maybe he decides to combat psychosis by going back to school to become a psychiatrist. He then decides to start fresh in Illinois, where he is assigned to treat a young boy who murdered his sister.
This theory actually makes so much sense that the only real reason to doubt it is that John Carpenter hasn't yet confirmed it as truth. It explains why Loomis isn't like a normal psychiatrist. He feels a personal duty to try and stop Michael as if this is a second chance for him. When Michael escapes and starts murdering, it would only make sense that Loomis would go on a crusade to stop him with the same obsession as Ahab seeking his white whale.
A real condition, CIP is basically the inability to feel pain. Taking stab wounds, bullets, and third-degree burns in stride, Michael doesn't seem to let pain hold him back. The absence of any pain indicator would also explain his complete lack of empathy for his victims.
He also uses this condition to his advantage in his workout routine, putting in extra reps to get the strength of 10 gorillas. (Why they are letting him use the Smith's Grove Sanitarium weight set at this point is another question.)
Some have suggested that Michael is autistic. He doesn't speak, exhibits repetitive ritualistic behavior, is obsessive, and has problems with his motor skills. His obsession with the day Halloween could be attributed to a diagnosis of autism, as well as his compulsion to kill people in the same ways over and over (though of course, murder itself is not an autistic trait).
Michael seems to lack the ability to comprehend theory of mind (that other people are living, thinking creatures just like you), which is traditionally a defining characteristic of autism. His complete lack of empathy would seem to be the result of an extreme deficiency in that area. As Dr. Loomis says, "I met him, fifteen years ago. I was told there was nothing left; no reason, no conscience, no understanding; and even the most rudimentary sense of life or death, of good or evil, right or wrong."
This one makes too much sense. In Halloween III: Season of the Witch, we follow the Silver Shamrock company, which uses killer masks as a ploy for a guy to usher in a new age of witchcraft. It has nothing to do with Michael Meyers... or does it?
According to this theory, the clown mask that Michael wears at the beginning of the original Halloween is a beta test of the masks that we see in Halloween III. The mask grants him immortality (that's why he can't be killed), but it has the unintended side effect of making him go crazy and kill his family (and just about any other random person in his path).
Seeing this, Silver Shamrock decides they need to work out some of the kinks.