This is a question, that bothers me every time I hear it. A part of me feels guilty, because I don't identify with the common answers people regurgitate (parent, celebrity, religious figure).
Another part of me feels that anytime I hear the above trinity of hero figures, it's a cop out. I also have trouble defining what a hero is, I can only assume that everyone has a definition that is personal to them, and so I let the above thoughts ebb away.
Here's the thing, I think I figured out something that could work for me. While chatting with a friend, I encouraged her to do what I thought she did amazingly well (website down). I told her that she was my self-accountability hero.
It clicked for me at that moment! I have many "heroes", they're just really great at the something I most appreciate about them. The thing that humanizes them, and makes me believe that I could do this too!