Michael’s murder of Bob, and his head tilt, is the scene where he’s both the most human and inhuman; inhuman because of his greater-than-average strength (he lifts Bob with just one hand), human because for once, he isn’t reacting to his actions like a robot programmed only for stabbing.

In 2018, ahead of David Gordon Green’s “Halloween” sequel (where Castle returned as the Shape), the actor discussed the head tilt moment with Entertainment Weekly. Castle said it was all John Carpenter’s idea and he only learned about it while they were shooting:

“John had me stand and look at the character, and I was behind the mask, and while the camera’s rolling he said, ‘Okay, tilt your head to the right, now tilt your head to the left.’ I had no idea what he was trying to get at until I saw the movie and I said, ‘Oh, how cool, it looks like I’m admiring my kill.’ That was John’s kind of inherent talent, coming up with that idea.”

On a “Halloween” commentary track recorded with Curtis, Carpenter describes Michael’s head tilt as resembling how one might “look at a butterfly that’s stuck,” while Curtis compared it to how a hungry dog moves its head.

Rob Zombie’s 2007 “Halloween” remake (which we’ve argued is underrated before) changes the site of Bob’s (Nick Mennell) death to a stairwell, but the shot sequencing is near-identical and Michael (Tyler Mane) still tilts his head at the corpse. In a small but consequential difference, though, the low angle framing makes it harder to notice the head tilt than in the original.

No one makes a movie quite like John Carpenter does.