Dr. Sam Loomis is often referred to as Michael Myers' nemesis, yet the Halloween slasher never really seems too concerned with killing his foe. It's been illustrated over the course of ten films - with an eleventh coming in fall 2021 - that Michael is capable of killing a victim extremely quickly, even before he became more explicitly supernatural in the later entries. Taking a life has never been a struggle for the man wearing a repurposed William Shatner mask.
Conversely, while an experienced mental health professional and presumably quite intelligent, Dr. Loomis (Donald Pleasence) is very much a normal human being. He doesn't possess any of the extraordinary amounts of pain tolerance and physical resistance to damage Michael has shown dating back to John Carpenter's original Halloween, which ended with Loomis pumping him full of bullets and sending him falling off a balcony. Yet, Loomis managed to survive for movie after movie and was never even killed onscreen in the original Halloween continuity.
Could Michael not killing Loomis simply mean he thinks his former doctor is not worth the effort or is there some shred of Michael Myers that remembers Loomis trying to help him as a child? It's a question worth asking, but also one where the answer isn't simple. The mind of Michael Myers is a complex place, to say the least.
All The Times Michael Could Have Killed Loomis In Halloween
Michael Myers not trying to kill Dr. Loomis in the original Halloween is actually excusable, as the two don't share the same space for very much of the running time. Loomis is hunting for Michael, while Myers is stalking Laurie Strode and her friends. By the time they do run into each other, Loomis gets the drop on Michael with his gun. In Halloween 2 though, Michael and Loomis have a close quarters face-off near the end, and when Loomis runs out of bullets, Michael simply gives him a quick stab in the gut and resumes approaching Laurie Strode. It's not even a very deep plunge of the scalpel, which is odd, since Michael lifted a nurse off the ground with it earlier.
In Halloween 4, after Michael has awakened from his coma and escaped the ambulance transporting him, Loomis tracks Michael to an isolated gas station. They have a brief encounter, albeit from across a room, in which a desperate Loomis - now scarred up and walking with a limp following the explosion at the end of Halloween 2 - begs Michael not to return to Haddonfield, going as far as offering himself up to be killed. Instead, Michael leaves but triggers an explosion that Loomis narrowly escapes. Then later on, Loomis attempts to stop Michael from getting to his niece Jamie, but he tosses Loomis aside instead of snapping his neck or slashing his throat. A confrontation near the end of Halloween 5 ends similarly, with Michael giving Loomis another quick stabbing and throwing him away. Halloween 6 leaves Loomis' fate vague, but it seems clear Michael didn't kill him. Then when Halloween H20 reset the timeline, it says Loomis died a retired old man.
Why Doesn't Michael Just Kill Loomis?
Michael, being the strong silent type, was never going to be someone who explained his actions. That doesn't preclude some educated guesses though. One possible reason, and perhaps the most intriguing, is that whatever shred of humanity might still be left in Michael does remember the years Dr. Loomis spent earnestly trying to help his young patient. While Dr. Loomis' focus did eventually shift to trying to keep Michael imprisoned for the good of others, he by no means made a cursory effort and then abandoned Michael. He cared, and that even comes through when he talks to Michael in a few of the later sequels, such as in Halloween 5, when Michael even seems momentarily affected by what Dr. Loomis is saying.
On the flipside, Loomis himself dubs Michael as being "purely and simply, evil." and if that's true, there could be a much more sinister reason he lets Loomis live. He might allow Loomis to go on just so that his former doctor has to continue to live with his repeated failure to stop Michael Myer's latest murder spree, no matter how desperately he tries. There's also the fact Michael is usually focused on killing his relatives, but that doesn't really explain him not killing Loomis, as Michael readily slaughtered other people who weren't family that happened to cross his path.
How The Rob Zombie Halloween's Approach Michael/Loomis
With his 2007 Halloween remake and its 2009 sequel, writer/director Rob Zombie threw a wildcard into the mix when it came to Michael Myers and Dr. Loomis' relationship. The dynamic between the two changed quite a bit, with Loomis forming a bit of a bond with young Michael, but seeming to lose whatever that was when Michael's mother killed herself in despair at what her son had become. After that, Michael spends the next fifteen years completely mute and disassociated from the people around him. Rob Zombie's take on Loomis seems more interested in using Michael's case for fame than helping him, although he does appear to have an attack of conscience when he encounters Michael and tries to save Laurie at the end of the remake. To that end, it very much did look like Michael killed Loomis, although the sequel revealed his survival.
In said sequel, Loomis didn't appear to have learned much from his prior experience, having written another book to try and capitalize on his life as the psychiatrist of a monster. Loomis in Halloween 2 becomes almost completely unlikable, acting like a fame-hungry jerk, again only seeming to regain his humanity enough to care about others when Michael surfaces and targets Laurie. Loomis attempts to intervene but gets absolutely destroyed by Michael in the process - in a way that Michael in the original Halloween continuity could've easily done at any point, but for some reason chose not to. Perhaps Zombie did this to illustrate how his Michael and Loomis were different from John Carpenter's iteration. In the director's cut, Michael even speaks, yelling "Die!" before stabbing Loomis, although an argument could be made for the latter's survival in this alternate finale.