First and foremost - the fear that someone will actually read what you've written. Shock. Gasp. The Horror! The Horror! But isn't that the point? Isn't that why you are putting pen to paper? Do you know what they call a story that you never share with anyone? A diary. Not that diaries are bad. In fact, they can be a great place to start sometimes. Dumping your most raw emotions and feeling onto the page. One could argue that everything anyone writes is somewhat autobiographical because it's the writer's unique perspective - their view on the world and the story they are telling. But an unshared story is a diary, a journal. Nothing more. Give it to someone. A friend, a relative, a friendly relative. Now, you've got yourself a story.
The fear that what you write won't be any good. Most of the time, this is really a veiled fear. Chances are there will be some good to be found in anything that one puts time and effort and thought into doing. What the fear really boils down to is that the finished work will not be the best it could possibly be. Here's the secret. It never is. Even the work that I am most proud of in my career could be better. There's always another round of revisions that could be done. More tinkering. A tweaking of dialogue. Finding a word that fits better than "rancid." It never ends. But, you have to make it so. You have to find that point in time, that line in the sand where you say - this is it. This is the work I have created, and let the chips fall where they may. Again, whether it's for publication or being submitted as a sample to garner work. Eventually, you have to pull the trigger.
The fear that people will laugh at you, mock you, or even loathe the very words you put on the page. Well, this may all very well happen. Chances are, there will be somebody somewhere who doesn’t connect with your work. It happens. But, you cannot put too much stock in the anonymous ranting of people filled with vitriol. That's not to say their opinion isn’t valid for them, but it doesn't mean that it needs to shape your life and your life's work. You'll never please everyone, nor should you try. You write the story you want to tell. That's it. As the guy who wrote the Rise of Arsenal, I can attest to that. There were people who reviled the book. I believe one even referred to it as the worst comic they ever read. Hyperbole, but still - wow. But for every negative review or comment, I could offer a positive one to counter it. For every person who blasted me for writing such an unreadable story, I had people telling me how much they were affected by the story. Tomato. Tomato. That works better verbally, but I think you get my point.
The fear of rejection. That can be the biggest fear. The fear that you will submit your work to the powers that be - whoever that is in whatever industry you are exploring - and it will be met with rejection. You should know that it happens to everyone. I believe even Stephen King got something like 100 rejection letters before selling his first book. Truth be told, I was at a crossroads of sorts, wondering if I'd ever sell anything as a writer, when I sold my first story to Marvel. X-Men Unlimited #1 (check it out, if you can find it!). That was my very first paycheck for writing. I actually made a copy of the check that I still have. It had Spider-Man on the check. I mean, how cool is that? But selling that story came after years of rejections, close calls, and false starts. It can be easy to get discouraged, but you can’t let it. You just have to keep going. Keep pushing. Have a PLAN B - a day job that pays the bills and provides for you and the family, but make time for your writing. Do what you need to do first, then do what you want to do.
Which brings me to the only real fear that matters. The only real fear that you should be worried about. The fear of doing nothing. If you stop writing or drawing or singing or acting or building or whatever - if you keep everything locked away in a filing cabinet, never showing it the light of day - if you never take that chance, you'll have nobody to blame but yourself. You can’t blame editors or the marketplace or the state of the industry or the timing or nepotism or geography. It will all be on you - because you were afraid to take a chance. Afraid to try. Afraid to go after what you want. Fear is always going to be there. The only question is does it stop you or not.