10. The Second Clone Saga
The first "Clone Saga" was published in 1975; and was an exciting, well-written story which ended in a groundbreaking twist virtually unseen in comic books at that time. I still own an original copy of those issues of "The Amazing Spider-Man". The second "Clone Saga", published 19 years later, remains one of the most controversial storylines in comic book history. The very concept that the person we all believed to be the real Peter Parker was actually a clone infuriated countless people. Famously, it was Marvel's intention to have that remain the case. The unprecedented backlash by Spider-fans forced the publisher to rewrite that plan. Think about that. For nearly 20 years, Spider-Man would have been an imposter. And the real deal Webcrawler? Now renamed Ben Reilly, he would have spent all that time traveling the world living a lie force-fed upon him. Sounds like the plotline of an awesome sci-fi movie.