When he first killed his older sister Judith Myers on Halloween night, he became a slasher whose power came from the curse of Thorn. He was locked away for his crime for over fifteen years, until he broke out of the institution and started killing people again.
Michael Myers had a very bad case of schizophrenia, and it was believed that he had been in a coma for over a decade after his crime. He was treated by Doctor Samuel Loomis and eventually was able to return to his hometown of Haddonfield, NJ and resume his rampage.
He was a very ruthless killer who ruined lives and left scars that would last forever. We've seen him be stabbed, shot and burned on screen before, so it's a bit surprising to see him chilling in the sewers of Haddonfield four years later, acting like he's still got it.
During Halloween 1978, Laurie Strode stabbed Myers in the left eye with a coat hanger, and this certainly seems to have changed his face. Nevertheless, it's worth looking at how the original movie depicted his face.
What's more, we can look back at a few other occasions when the serial slasher's face was changed in different movies. In Halloween Kills!, we get to see a brief glimpse of Michael without his mask.
Likewise, we also get to see the serial slasher being dragged through a house by a rope, and his scythe impaled Spitz on a pitchfork during the Tower Farm party. It's a great look, but it doesn't really do much to change the image of the Shape that we've grown to know and love.