I was frightened very easily as a child. At the age of either 2 or 4(I can't remember which trip it was), I cried hysterically at the heffalump part of the Winnie the Pooh ride. My parents definitely weren't expecting that!
I refused to go on a lot of rides till I was in the double digits, including (but not limited to) Dinosaur, Snow White's Adventures, Pirates of the Caribbean, any 3D films, etc...
The Haunted Mansion was my worst fear at Disney. When I was 9, my parents told me we would only go to DW if I agreed to ride it. Of course I said yes, but I shut my eyes the entire time on the ride.
I wasn't often afraid of the thrill rides. I rode ToT for the first time when I was 7.
The animatronix were what freaked me out. They just look so real! I still shy away from them if the ride cart gets too close for my liking. I sit in the middle of a ride whenever possible.
Also, my Dad and I were the first ones on the PotC on our trip this year. No one else was on the ride. PotC may not seem scary when the boats are full, but let me tell ya, it is sooo scary when it's just you! Especially in the beginning! It was my first time seeing the mermaid feature, so I thought they were going to pop up or something! The cannons also had a blast of air which hit your head that hadn't been there my previous trip. It just felt like something was wrong because I was so used to all of the people.