This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Final Fantasy: The Spirits Within
Even more than their Random Encounter ability, consider that even if you survive your initial encounter with one, it can leave a piece of itself in your body that will grow inside you and devour your soul.
The phantoms don't just touch you; they seize your immortal consciousness, pulling and tearing it, screaming, from your body to consume it.
"I try to imagine what that must have been like. Seeing everyone around you fall over dead for no apparent reason. And then, at the end, feeling something next to you. Invisible. Touching you. Reaching inside your body and—"