The scariest dream I can think of is one I had when in intermediate school. Must've been mid-70s. I was probably 11 or 12.
I was in the school auditorium of IS 144 in The Bronx. I remember trying to get away from someone with a syringe. Whatever was in this syringe, it was dangerous, probably a deadly poison. I was trying to quickly make my way through a row of seats, but then another kid came in from the other end and approached me also. I was trapped. As the one originally chasing me got closer with his needle, I said "No". I said it louder a second time. He was unperturbed. Finally I woke myself up yelling "NO!"