This reinvented the slasher genre. Freddy isn’t a mute brute; he’s a child murderer getting revenge on the parents who burned him alive. The practical effects (the wall stretch, the body bag in the hallway) still hold up. Best kill: Tina’s invisible death on the ceiling.
The initial run established the "Springwood Slasher" as a supernatural force born from the vigilante justice of vengeful parents.