Well, there's 'Voices in my head.' This implies that there are unknown voices inside one's mind, which could be a sign of possession or some otherworldly influence, and it's quite a scary concept.
How about 'Knock, no one there.' You hear a knock at the door, but when you open it, there's nobody. It leaves you with a sense of unease and the feeling that something is playing tricks on you.
Here are some: 'Alone in the dark.' It creates an immediate sense of isolation and the unknown that lurks in the darkness.
Footsteps in the attic. Alone in the house, hearing those footsteps in the attic is really terrifying. You don't know what's up there, and every step seems to be getting closer, sending shivers down your spine.
Lights flicker, shadow grins. The sudden flickering of lights often creates an eerie atmosphere. And when you catch a glimpse of a shadow that seems to be grinning, it's truly spine - chilling. It makes you question if there's something malevolent around you that you can't quite see clearly.
The mirror shows nothing. It's as if there's no reflection, just an empty, black void where my face should be. This makes me wonder what is lurking in that emptiness, ready to reach out and grab me.
Here are some: 'Alone in the dark.' It gives a sense of isolation and the unknown in the darkness which is quite terrifying. Another one could be 'Footsteps, no one there.' Just the idea of hearing footsteps but seeing no one is really spooky. And 'Lost in the forest' also works. Being lost in a vast and often unpredictable forest is a nightmare scenario.