This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Freddy's Dead: The Final Nightmare
Much-maligned as it is, the film gave Freddy some straight-faced, creepy moments, such as his standing in a windswept cellar doorway and gloating "every town has an Elm Street", and later threatening his long-lost daughter with the line "I didn't need a glove to kill your bitch of a mother, and I don't need one to kill you". Despite the jokes, Robert Englund could always make Freddy terrifying again at the drop of a dusty old fedora.
Even though present day Freddy is super hammy and funny, in Maggie's childhood memory Englund plays him completely straight and very menacing. It also establishes Freddy not as a creepy loner but as a seemingly ordinary family man, which makes him even more disturbing.
Tracy meets Freddy in her dream, appearing as her father, who molested her and it is implied she killed in self-defense. He proceeds to feel her up, try to make her kiss him, and triggers her to the point that she bashes his face in with a kettle, which does absolutely nothing to faze him.
There is a brief, genuinely creepy moment in one of the otherwise very silly scene where Freddy Krueger takes away the nearly-deaf Carlos' hearing aid... and absolutely no sound plays as Freddy Krueger walks behind the confused Carlos, shouting at him, flailing about... being deaf, KNOWING that he's there, but having nothing BUT your sight to spot him is actually pretty creepy.