Pamela and Jason Voorhees
Generally, any slasher film is going to have you rooting for the villain at some point, only because the victims can be so stupid sometimes. In the case of the original Friday the 13th franchise, you should be rooting for the villains because they’re right.
In the first one, if you recall, Jason’s mother Pamela was the machete wielding killer. Her son, Jason, was an outcast, deformed and bullied by the other kids at Camp Crystal Lake. When he tried to prove that he could swim, he drowned. All Pamela wanted was for her son to have a few weeks of normalcy, but instead, the worst counsellors in the world let her son die. So she figured she’d do what she could to ensure Camp Crystal Lake didn’t reopen.
Then, after one of the counsellors decapitated his mom, Jason had to come back from the dead to avenge her, because that’s what you do when someone hurts your mom. You pay them back – that’s not homicide, that’s being a good son.
Plus Kevin Bacon had it coming.