Spider-Man 4 was to be the fourth film in the Spider-Man series, starring a 35-year-old Tobey Maguire as the teenage titular character. It has been scrapped in favor of a reboot, having succumbed to Supervillain Inflation Syndrome.
After a decade of rumors from fans that James Cameron would make Spider-Man his post-Titanic film franchise (he wrote a treatment for the film that is widely available on the Internet) Cameron instead chose to focus his time on doing absolutely nothing for an entire decade.
Instead of getting the director of Aliens and Terminator 2, fans wound up with the director of The Evil Dead 2, Sam Raimi, which most did not realize at the time was an upgrade.
The original Spider-Man was released in 2002 and set the all-time record for opening weekend grosses. It was widely not hated.
The Green Goblin.
... arrived in 2004 and somehow became one of the best-reviewed films of all time, according to its 94 percent positive rating on RottenTomatoes.com. That means it scored exactly the same as No Country for Old Men and The Dark Knight, and was considered by critics to be a better film than There Will Be Blood, District 9 and Inglourious Basterds. Many film experts say this proves that judging a film's worth by its RT score is retarded.
Naturally, since it was the most critically acclaimed film of the series, it was also the least successful worldwide. However it still wound up as the #2 film of 2004 in America, behind Shrek 2 and ahead of The Passion of the Christ. This reaffirms the commonly held belief that as a pop culuture icon, Spider-Man ranks behind Shrek but ahead of The Lord.
Doc Ock, Harry Osborn.
...debuted in 2007 and was widely regarded to be a turd. It also contained a massive "retcon" of the storyline (that is, a retroactive rewrite of a previous plot point in the mythology for the purposes of the current story) which would be fine if they weren't retconning a crucial plot point that just happened two movies ago.
The film's writers then fell into the same pitfall that ensnares nealry all comic book movie writers: Supervillain Inflation Syndrome. Rather than exploring the character in greater depth or challenging the audience's notions of what it means to be a superhero, the writers simply choose to cram in as many villains as possible. This might possibly have something to do with selling action figures.
Once the number of villains reaches three--the maximum number science says is possible in a feature-length film without robbing each of the screen time needed to develop them fully as a character--the franchise collapses and must be rebooted, preferably with just one villain (though two is possible).
Sandman, Venom, Green Goblin II
...will apparently never be filmed. Tobey Maguire and Sam Raimi have walked away from the project, and the studio has decided to "reboot" the franchise, Dark Knight-style, to debut in the Summer of 2012.
The now-canceled project was to again include the fatal number of three villains, tentative plans mentioned The Lizard (Dylan Baker) The Vulture (John Malcovich) and The Vulturess (Ann Hathaway).
Critics lament the loss of the film, as many believe it had the potential to be ridiculous in a way that would have altered our culture forever.