Why Did Michael Myers Kill His Sister In Halloween?

Few franchises can say that they've endured the way that "Halloween" has. Directed by the horror master himself, John Carpenter, the 1978 classic that started it all remains one of the most beloved movies the genre has ever produced. It also resulted in a series of sequels and reboots that have allowed Michael Myers to endure for nearly 50 years in the larger pop culture consciousness.

Carpenter's original movie sets the tone right out of the gate, with a young Michael Myers killing his older sister, Judith Myers, in a brutal fashion. We see the whole thing in POV before the gut-punch of a reveal that it was a young boy behind this cold-blooded murder. The rest of the film picks up years later, with Michael now an adult let loose on the town of Haddonfield, leaving quite a few more bodies in his wake.

But why did that young boy decide to kill his sister in the first place? The answer is actually pretty complicated and has more than one answer. That's because the overall "Halloween" timeline is pretty convoluted, with multiple branches and continuities to follow depending on which movie/movies we're talking about. Tricky or not, we're going to offer up the various answers to that question, accounting for the explanations offered by the various timelines. Let's dive in.

The thing about "Halloween" is that it is a very scary movie and has been since 1978. That's something that Carpenter really leans into by having Michael Myers referred to as "the Boogeyman" in the movie itself and "The Shape" in the credits. He's mysterious and, in many ways, pure evil. That gets at the heart of why he killed his sister in the first place.

As Dr. Samuel Loomis (Donald Pleasence) explains in the movie rather famously, he spent a full 15 years with Michael following the infamous murder of his sister, Judith. Nobody knows Michael quite like Loomis, and it's worth looking back at his monologue about Haddonfield's Boogeyman to figure out why Judith met such a grim fate. As he mused:

"I met him 15 years ago. I was told there was nothing left. No reason; no conscience; no understanding in even the most rudimentary sense of life or death, of good or evil, right or wrong. I met this six-year-old child, with this blank, pale, emotionless face and the blackest eyes. The devil's eyes. I spent eight years trying to reach him, and then another seven trying to keep him locked up because I realized what was living behind that boy's eyes was purely and simply ... evil."

Put simply, Michael Myers is pure evil, and that's why he killed Judith. That's scary in its own way because it's hard to make sense of it. It's not about reason. This was something that was carried over to the timeline in 2018's "Halloween," and it was also more or less the explanation offered by Rob Zombie's ever-divisive "Halloween" movies. Michael is always evil, that much is certain, but evil isn't always the reason he killed Judith.

This is where things get a little weird when it comes to Michael Myers and the "Halloween" franchise in general. After "Halloween III: Season of the Witch" failed to kickstart the idea of turning the franchise into a series of anthology films, Michael returned in "Halloween 4: The Return of Michael Myers." That kicked off a bizarre trilogy of films within the canon of the franchise, with "Halloween 5: The Revenge of Michael Myers" following. Things got exceptionally bizarre when "Halloween: The Curse of Michael Myers" arrived in 1995.

For one, it's worth noting that "The Curse of Michael Myers" is not well regarded in the "Halloween" movie canon. That's why the franchise was retconned in the years that followed. Even so, it did introduce some big ideas, including a brand new reason why Michael killed Judith. It all has to do with a group known as the Cult of Thorn. While one could write an entire article breaking down the cult itself, we're going to go over the basics as they relate to this situation.

Very basically, The Cult of Thorn was a cult of druids, one that aids an ancient evil known as Thorn, who can bestow great power onto someone. Whoever takes on the power of Thorn is forced to kill their family. By the end of "Halloween 6," it's revealed that Michael Myers was chosen by the Cult of Thorn as the vessel, which is why he killed Julie. 

There are different versions of "The Curse of Michael Myers" and the whole Cult of Thron part of the franchise is something that could be discussed ad nauseam. It's a far more wacky explanation for Michael's killer instincts, that much is certain. This notion would be abandoned by the time "Halloween H20" came out a few years later in 1998, with that film serving as more of a direct sequel to "Halloween II." 

This all brings us back to Laurie Strode. Played by Jamie Lee Curtis, she is the primary protagonist of the "Halloween" films. Michael Myers has it out for her pretty much from the very beginning. No matter how many bodies he leaves in his wake, his sights always return to Laurie, right up until her death in "Halloween Resurrection," or right up until Michael's death in "Halloween Ends," depending on which timeline we're following. Either way, looking at Judith's murder begs the question, why does Michael also want to kill Laurie so badly?

The answer depends entirely on which timeline we're following. In "Halloween II," which John Carpenter isn't personally a big fan of, it introduced the idea that Laurie Strode is also the secret sister of Michael Myers. If we're following the original timeline, or Rob Zombie's films, this explains why The Shape would want to kill Laurie. He killed Judith, so there's perhaps something about finishing the job at play here. Michael is pure evil, and a lot of the time, that evil can seem a bit aimless. Laurie is where he finds his aim.

If we follow the "Halloween 4" timeline, Michael wanting to kill Laurie is all about completing the task foisted upon him by the Cult of Thorn. If Laurie Strode is his flesh and blood, then she must die. It's as simple as that, even if the specifics of the Cult of Thorn and the movies they're a part of can be a bit convoluted.

Lastly, there's the matter of the 2018 "Halloween" trilogy. David Gordon Green's movies serve as direct sequels to the original, ignoring every other entry in the franchise. Green's "Halloween" movies changed things up by making it clear that Laurie isn't Michael's sister. So, in this timeline, we get back to the more simplified idea that Michael is pure evil. Is unfinished business at play? Sure, but it's not family ties or some cult behind it. It's seemingly unstoppable, highly-motivated evil, plain and simple.