5. X-Men (2000)
With comic-book movies being released on an alarmingly regular basis these days, it's hard to believe that by the late 1990s only Superman and Batman had made the transition from page to screen with any real critical or commercial success. Although the rise of the comic book movie can arguably be traced back to the release of the R-rated Blade in 1998, the first mainstream box-office hit in over a decade came with Bryan Singer's X-Men. After being stuck in development hell since 1989, Singer was announced as director in late 1996 but it would be almost three years before the $75m-budgeted movie even began shooting. Featuring a sprawling ensemble cast (including the now-famously unknown Hugh Jackman), the movie suffers from an over-abundance of world-building (which is to be expected given the convoluted nature of the plot) but the chemistry between the actors is great and the CGI and wire-augmented action scenes are hugely enjoyable. A critical and commercial success, X-Men would take almost $300m at the box office and just like that, the superhero boom began. Within five years we had an X-Men sequel, two more entries in the Blade franchise, two Spider-Man movies, Daredevil, Hellboy, The Punisher, Elektra, Catwoman, and The Fantastic Four to name but a few. If X-Men hadn't been a success when it was released, studios may not have been so willing to greenlight an abundance of superhero flicks. Without this movie, would the Marvel Cinematic Universe even exist?