i would have to say in my top 5...
1.) myself: i fear the things i'm capable of when i'm afraid or upset or depressed and so on. i fear the potential withing me therefore i fear myself in every way.
2.) being alone: i fear almost as much as i fear myself that i will end up alone and forgotten by the world. i fear that because i am who i am people will reject me and in the end even animals wont remember me when i'm gone.
3.) death before fufillment: i fear that i may die before i've fufilled my purpose in life or even began to enjoy life to its fullest.
4.) rejection: i hate the idea of rejection because it makes me feel like i'm less than human when people i want to be around dont want me around. it makes me feel as if i'm beneath them and not worthy of their time and makes me feel that if i'm not good enough then... well, see #2.
5.) loss: i fear loseing someone or something close to me and never being able to get it back. i feel that if i where to lose the most important person in my life right now i would shut down inside and then i really would be less than human because i feel that our emotions define our humanity. without emotions, we're walking rotting corpses with little more than animal instincts.
those have to be my top 5 biggest fears. there are a lot of smaller ones like heights and such but these 5 are the foremost in my mind on the constant. they're not in order or anything because i really dont know what my biggest fear is but they're all pretty daunting in my life.