My own mind. Losing myself. People. Being judged. Public speaking. Being alone or feeling alone and lost. Living with no compassion. Failure. Losing loved ones, friends, even people I don't know because I feel their pain. Being out of my wits; sadly this makes the fear likely to perpetuate.
I can play any horror game no matter how twisted and I shake it off like "meh", but when the above things mess with me, I'm paralyzed in fear.