Most common fears I can base my concepts on:

1. Fear of flying
2. Fear of heights
3. Fear of the dark
4. Fear of death/dying
5. Fear of failure
6. Fear of spiders
7. Fear of dogs
8. Fear of dentists
9. Fear of snakes
10. Fear of needles
11. Fear of being alone
12. Fear of Gods
13. Fear of clowns

http://www.selfhelpcollective.com/most-common-fears.html