Most studio executives and producers wouldn't dream of ever making a movie without having a complete script before cameras shot a single second of footage. After all, its hard to attract talent to a project without giving them an idea of what they are signing up for, and its even harder to entice investors into spending money on a film without showing them an idea of what the finished product will be like. In many ways, trying to shoot a film without a script seems like trying to build a house without a blueprint. That doesnt mean that movies have never gone into principal photography without a final draft of the script. Because of various reasons - including creative disagreements, production schedules, and financial issues - several movies have started filming without a finished screenplay. It's not just movies trying to keep costs low, either; plenty of huge Hollywood blockbusters were shot as the movie was being written. While for many this has led to disastrous results, for some not having to stick to a completed script added creative sparks to the finished product. The following ten examples range from movies that became classics despite starting filming without a script and others that really needed more planning in the script department before shooting began.