Billed as Superman the Motion Picture with the tag line, "You will believe that a man can fly", this was the first big-budget super hero movie. Stories about production problems had been going on for years before the movie made it to the screen. For a long time it was considered a "troubled production". When it actually came out it was a huge hit.
Part of the success was the contrast between the earnest, too-good-to-be-true Clark Kent/Superman and the post-feminist, post-Watergate Lois Lane.
The movie started on the doomed planet of Krypton, showing us Jor-el sending his son to the Earth and educating him at the same time. It followed as the child was adopted and brought up with solid mid-western values, eventually discovering his heritage and assuming the identity of Superman. We saw Clark meet Lois then rescue her as Superman. He then went on to save multiple people (and rescue a cat from a tree).
Unfortunately the movie peaked half-way through. Once Luther and his goofy assistants were introduced it was all downhill into camp.
Superman 2 never duplicated the lyrical parts of the first movie and never got quite as campy. Superman fought a trio of villains with the same powers that he had. He was also pulling powers out of a hat. After that, the movies went downhill fast.
Superman was notable for its visual effects, particularly the digital wire removal. It proved that comic book heroes could appeal to adults if taken seriously.
The comic book character was notable for going through two reboots in the 1960s. The first one trimmed the cast eliminating Batwoman, Batgirl, Batdog and Bat Mite. Also eliminated were fights involving giant props, the Batplane and whirlybats (flying chairs). The over-sized Batmobile was traded in for a convertible sports car. Plots involving aliens or wacky villains were dropped in favor of a more realistic approach. Then came the campy TV show and a lot of the camp crept back into the comic. By the late 1960s, the character was being redefined again. Robin was sent to collage and everyone started referring to him as the Batman.
This change was reflected in the approach to the character. Camp was banished. The Batman took himself seriously.
The look of the movie had a major effect on late superhero movies. The Superman movies were set in the present-day. Care was taken to reproduce the offices and street-front of the New York Times as the Daily Planet. While this added to the realism, it also meant that the Superman movies did not age well. By the mid-1980s, the first couple of movies already looked dated.
For Batman, Tim Burton designed a Gotham City that never existed. Few cars were shown and none were contemporary. As a result, this movie still looks fresh more than two decades later. The only jarring point is when we see Bruce Wayne looking at various TV screens. The TVs use picture tubes rather than flat screens.
The movie showed that a superhero movie did not need any camp or tongue-in-cheek to succeed. But, since it was a Tim Burton movie, it did have some bizarre touches. The sequel had more. The third and fourth movies were over the top and killed the franchise.
Several marvel properties had been made into movies but there were C-list characters (Blade) or flops (Howard the Duck, Punisher). This was the first A-list Marvel title to make it to the big screen and it was a hit. This was followed by an onslaught of other Marvel heroes which continues to this day. Most of them are true to the original character which was a problem in the earlier adaptations.
The X-Men also added sub-texts to superhero movies. The mutants could be seen as stand-ins for issues such as terrorism and gay-acceptance.
Superman showed that there was still a place for superheros in the cynical, post-Watergate era. Spider-Man showed that the same was true in the post-9/11 era. It was a huge hit.
Both X-Men and Spider-Man showed that superhero franchises did not have to sink into camp as they progressed. Both series stumbled on their third movie by stuffing too much into the plot but neither committed a sin equal to "bat nipples".
This movie introduced the concept of rebooting a character. I still prefer the Tim Burton version but without this movie no serious Batman movies would be possible.
This was the first marvel Studios movie and it introduced the Marvel movie formula. This includes a long middle act where we get to know the character. The casting and scripting on Iron Man were brilliant because this middle act is the best part. The movie actually becomes less interesting when Tony Stark starts fighting.
Where the X-Men kicked off movies featuring Marvel characters, this one began a series of movies produced by Marvel in which the characters share a common universe and interact. Without the previous four movies, the Avengers would have flopped. It would have taken too long to introduce the characters.
Iron Man was also notable because the head of the Academy of Motion Pictures admitted that it (and The Dark Knight which came out later the same Summer) should have gotten best picture nominations. This was a break-through in acceptance of superhero movies.
Another huge hit, this is the first superhero movie to win a major Oscar (best actor for Heath Ledger. No camp here.