Superhero movies are a popular and established genre of filmmaking, with multiple projects in development at any given moment from several studios in the gold rush to the box office. But the road from concept to your friendly neighborhood cinema is often bumpy.

RELATED: 15 Comic Book Origins Changed For The Movies

For every hit movie that makes it to the big screen, there are dozens more would-be blockbusters that languish in development hell, with treatments and scripts piling up in unread stacks. Other projects escape but hit roadblocks along the way, such as studio interference or actors, directors or producers dropping out over creative differences. A few manage to make it past those hurdles into production, but get scrapped while in progress. Here are 16 cases of what might have been.

16 SUPERMAN LIVES

Nicolas Cage in a Superman costume in a screen test for Superman Lives

One of the most famous killed projects, "Superman Lives" would have been director Tim Burton's bid to reboot the Superman movie franchise in 1998, almost 10 years after "Superman IV: The Quest for Peace." The story was based on "The Death of Superman" storyline from 1992 with a script by Kevin Smith. Nicolas Cage, hot off action films "The Rock" and "Con Air," and a Best Actor Oscar for "Leaving Las Vegas," was announced to star. But when Burton signed on to direct, he rejected Smith's script. Rewrites from Wesley Strick and from Dan Gilroy didn't click, and the bad box office returns from "Batman and Robin" led Warner Bros. to pull the plug.

Preliminary production photos of Cage in costume, and Smith's behind-the-scenes stories of how he was instructed to draft the narrative, tainted the project's reputation. However, the 2015 documentary "The Death of 'Superman Lives': What Happened?" covers the development, progress and end of the project, and makes the case that the movie might have been better than people think, had it been realized.

15 SPIDER-MAN 4

Spider-Man

The first and second films in director Sam Raimi's "Spider-Man" series were big hits, but "Spider-Man 3," featuring an emo Peter Parker and villains the Sandman and Venom, left a sour taste. Raimi particularly didn't like a studio directive to shoehorn Venom into the story and neither did critics. Plans went forward in 2007 for a fourth film, with Raimi wishing to improve on the previous movie. Mysterio and the Vulture were slated to be the villains, and possibly the Lizard, as Dr. Curt Conners had appeared in "Spider-Man 2" and "Spider-Man 3."

However, the script went through four drafts, none of which pleased Raimi. With production looming, Raimi suddenly announced in 2010 he couldn't meet the May 2011 release date. In an interview with Vulture, he said, "I was very unhappy with 'Spider-Man 3,' and I wanted to make 'Spider-Man 4' to end on a very high note, the best 'Spider-Man' of them all. But I couldn't get the script together in time, due to my own failings, and I said to Sony, 'I don't want to make a movie that is less than great, so I think we shouldn't make this picture. Go ahead with your reboot, which you've been planning anyway.'" With Raimi out, star Tobey Maguire withdrew as well.

14 BATMAN BEYOND

Batman Beyond

"Batman Beyond," the 1999-2001 Kids WB animated series, was considered for a live-action film in 2000. Set in 2039, 20 years after Batman's retirement, the show has teenager Terry McGinnis take over with training, equipment and mentoring provided by Bruce Wayne himself. "Batman Beyond" co-creators Paul Dini and Alan Burnett, along with writers Neal Stephenson and "Remember the Titans" director Boaz Yakin, developed a script for Warner Bros. in 2001.

In an interview with IGN, Yakin called the story "almost like Sam Raimi's 'Spider-Man' but a little bit darker -- a teenage, kind of futuristic, cyberpunk Batman thing." However, Yakin lost heart in the project and backed away, saying, "It was just one of those moments in time where you think you want to do something, and then you realize you don't really want to do it, and for some reason it's on your IMDb page for the rest of your life." Warners passed on "Batman Beyond" in August 2001 in favor of "Batman: Year One," which also didn't get made.

13 SANDMAN

Sandman by Neil Gaiman

Neil Gaiman's "Sandman," which ran for 75 issues in 1989-1996 (the last half under DC's Vertigo banner) was a critical and commercial success, making the New York Times best-seller list. An early attempt at a movie in 1996 by Warner Bros. floundered, and a subsequent bid failed as well. The project was in limbo until 2010, when HBO tried to make it into a series, but by 2011, Gaiman expressed displeasure with the results.

Then, producer David S. Goyer announced in 2013 that he would work with Gaiman and Joseph Gordon-Levitt to produce a "Sandman" movie, with Gordon-Levitt also slated to direct and star. In 2015, Warner Bros. chose to shift its Vertigo-based films to sister studio, New Line Cinema, and brought on Jack White to draft a new script, and then Eric Heisserer to rework it, leading Gordon-Levitt to back away in 2016.

In a Facebook announcement, Gordon-Levitt said, "I came to realize that the folks at New Line and I just don’t see eye to eye on what makes Sandman special, and what a film adaptation could/should be." Heisserer left the project a few months later.

12 SUPERMAN REBORN

Christopher Reeve as Superman flying

The "Superman" series of films with Christopher Reeve whimpered to a miserable end with 1987's flop "Superman IV: The Quest for Peace." However, Cary Bates (longtime scribe for DC's "Superman" titles who also wrote for the syndicated TV show "Superboy") proposed an idea to producer Ilya Salkind to jump-start the franchise. Salkind and father Alexander Salkind, who produced the first two fills, had reacquired rights to do "Superman" films after Canon Films' let its one-picture deal lapse.

Bates's script, credited to him, Ilya Salkind and Mark Jones, had Brainiac come to Earth, shrink Metropolis and put it in a bottle city, with Superman inside. Discovering Superman's presence, Brainiac shrinks himself to enter the bottle and do battle. Superman dies, but his essence is absorbed into the nearby bottle city of Kandor, where he is reborn.

Bates, in an interview with Newsarama, said the Salkinds put aside the project, wishing to first complete 1992's "Christopher Columbus: The Discovery." But by then, Warners started work on the TV show "Lois and Clark: The New Adventures of Superman" and ultimately moved to reacquire all rights to Superman, bringing both "Superman V" and "Superboy" to an end.

11 HAWKMAN

Hawkman flying on a blank background in DC Comics.

Hawkman, the DC character who is either a reincarnated Egyptian prince or a Thanagarian policeman, depending on which strand of continuity you wish to follow, has made a few appearances on TV, but hasn't had any luck in making it to the big screen. He first appeared in 1940's "Flash Comics" #1, created by writer Gardner Fox and artist Dennis Neville. The first news of a "Hawkman" film surfaced in December 2009 on the site Pajiba, calling it "part 'Indiana Jones,' part 'Da Vinci Code' and part 'Ghost'," and stating that Warner Bros. intended to make a franchise out of it. No news followed until 2011, when the Pajiba blurb was circulated and discussed on several other sites. Hawkman did appear on TV in "Smallville," and was a significant part of the first season of "Legends of Tomorrow."

"Suicide Squad" did hint at a possible future Hawkman appearance in the DC Cinematic Universe, by having most of the action take place in Midway City, Hawkman's stomping grounds.

10 DAZZLER

Dazzler issue #12

The character Dazzler first appeared in 1980's "Uncanny X-Men" #130, but she was planned from the start to be in other media. Dazzler, jointly created by Jim Shooter, Tom DeFalco and John Romita Jr., was conceived as a collaboration between Marvel Comics (which would provide comics), Casablanca Records and Filmworks, which would provide a singer and make records, like The Archies.

As Shooter describes on his blog, Casablanca wished to introduce the character in a TV special, stipulating that it had to include several actors and musical acts under contract with the label. Shooter therefore drafted a treatment in four days that threw in roles for Cher, Donna Summer, The Village People, Kiss, Lenny and Squiggy from TV's "Laverne and Shirley" and Robin Williams, as well as the Avengers, Spider-Man, Rodney Dangerfield as the Lord of Chaos and lawyers Dewey, Cheatham and Howe -- and, of course, Dazzler.

Shooter's treatement impressed Casablanca to think bigger, meaning a feature film, so it shopped the treatment at the Cannes Film Festival, which got Bo Derek on board to star. This led to a bidding war for the property, Casablanca to commission a script from Leslie Stevens and Derek to demand that husband John Derek be the director, which killed the project dead.

9 BLACK PANTHER

Wesley Snipes Black Panther

Marvel's "Black Panther" starring Chadwick Boseman just began filming in Atlanta, but if things had gone differently, we would have seen Wesley Snipes in the role more than 20 years ago. In 1992, comedy and action star Snipes, riding high on the successes of "New Jack City" and "White Men Can't Jump," announced his intention to play the Black Panther that June, and was willing to do sequels.

His interest led Columbia Pictures to put a "Black Panther" film in development by 1994, with Stan Lee having a say. However, two years passed, with Lee not finding any of the scripts suitable, so in 1998, Joe Quesada and Jimmy Palmiotti were brought in to adapt the property. The project stalled over the years, and by 2002, Snipes had moved on to the first "Blade" sequel, but still said he wanted to star in "Black Panther." John Singleton, director of "Boyz N the Hood," was in the mix by 2007 as a possible director, but obviously nothing ever came of that.

8 SGT. ROCK

Sgt. Rock Arnold Schwarzenegger

After "Legends of Tomorrow" teased a Sgt. Rock appearance" with a poster showing his iconic helmet, Rock's first live-action appearance was a disappointing cameo in the first-season finale in which he was almost immediately killed. However, the seeds of a feature film for the legendary World War II soldier (created by Robert Kanigher and Joe Kubert in 1959's "Our Army at War" #83) have been germinating since 1980, under producer Joel Silver, a parade of top-flight scriptwriters and Guy Ritchie as director.

Improbably, Arnold Schwarzenegger was cast as the all-American soldier, with Rock changed from a Pittsburgh born-and-bred ex-boxer to a German immigrant fighting to throw off the Nazi yoke from his homeland. With filming slated for Europe in 1988, Schwarzenegger balked, not wanting to be away from his family for several weeks, and invoked a clause in his contract stipulating the film had to be shot in the United States, according to a 1988 New York magazine report. In 2008, Bruce Willis was floated as the lead in another Guy Ritchie-directed film. By 2010, the setting was changed from the 1940s to the near-future, but that still didn't sell the project.

7 100 BULLETS

Agent Graves holds a gun in 100 Bullets from DC Comics

The sprawling saga "100 Bullets," written by Brian Azzarello and drawn by Eduardo Risso, was a juicy crime noir conspiracy tale. The acclaimed Vertigo series, which ran for 100 issues, presented a mysterious man called Agent Graves who visits people with the gift of a briefcase. Within is what Graves describes as "irrefutable proof" of how someone has done wrong to the briefcase recipient, along with an automatic pistol and 100 bullets. Graves leaves it to the person as to what to do, but says using the gun will not bring any legal consequences: no investigation, no arrest, no prosecution. As the story unfolds, readers learn of a crime cabal called The Trust, its enforcers the Minutemen and several power plays between factions of both groups.

The first stab at adapting "100 Bullets" was in 2011 for Showtime, to be executive produced by David S. Goyer, but it was shelved in 2013 because of a spate of violent shootings in the United States. Tom Hardy, who was Bane in "The Dark Knight Rises," announced in 2015 he would produce and star in an adaptation for New Line Cinema. Leslie Jones, of "Saturday Night Live" and "Ghostbusters," tweeted a couple hints in 2016 that she's interested in taking part.

6 PLASTIC MAN

Plastic Man

In the wake of 1989's "Batman" from Warner Bros., other movie studios sought their own superhero properties. In 1991, Dreamworks and Warner secured the rights to "Plastic Man," based on the Quality Comics hero created by writer/artist Jack Cole in 1941. Plastic Man was Patrick "Eel" O'Brian, a hood who gains super-stretchy powers after getting exposed to an experimental acid.

Before Lilly and Lana Wachowski (then still known as Andy and Larry) hit it big with "The Matrix," they wrote a script for "Plastic Man" in 1995. Several liberties with the character were taken. Renamed Daniel O'Brien, he was an environmentalist who was captured by an industrialist and experimented on, and then seeks revenge. Nothing came of it, so the Wachowskis went on to other projects. After "Speed Racer," the Wachowskis revived interest in "Plastic Man," with a release announced for December 2009 and Keanu Reeves rumored to star, but nothing more happened.

5 Y: THE LAST MAN

y-the-last-man-vol-1

Writer Brian K. Vaughn and artist Pia Guerra helmed 60 issues of "Y: The Last Man" for Vertigo from 2002 to 2006, telling about a world in which every male mammal suddenly died save two: Yorick Brown and his pet monkey Ampersand. Yorick engages on a global road trip to find his estranged girlfriend, guarded by Agent 355 and accompanied by Alison Mann, a geneticist trying to discern why the plague struck and to find a cure for it.

New Line got the movie rights in 2007, with Shia LaBeouf suggested as Yorick. LaBeouf pulled out by 2009 and the project languished for the next five years. Wanting a standalone firm and not wanting to commit to a trilogy, New Line let the rights revert to Vaughn and Guerra. After that, it was shopped to cable network FX, which put it in development as an ongoing TV series in 2015, naming Michael Green showrunner in November 2016. At the Television Critics Association winter meeting in January, FX announced it is waiting on a script.

4 GREEN ARROW: ESCAPE FROM SUPER MAX

Green Arrow

"Arrow," which debuted in 2102, is the linchpin of the DC Television Universe, but Green Arrow was slated for the big screen in 2009. David S. Goyer, who wrote "Batman Begins," the "Blade" series and directed "Blade: Trinity," came up with a concept. Unlike most first movies about a hero, "Green Arrow: Escape from Super Max" would have skipped the origin save for flashbacks.

Co-written with Justin Marx, the story had Green Arrow framed and convicted for the murder of a government official. He is sentenced to a Super Max prison full of convicts and supervillains he's busted over the years. Among the convicts behind those bars were The Riddler, Lex Luthor and The Joker, as well as second and third-string villains like Icicle. Green Arrow forms alliances with some of the villains to escape and clear his name. The project lapsed, however. In an interview, Goyer said the leadership of Warner Bros. at the time wanted to just make Superman and Batman movies, and, years ahead of "Suicide Squad," didn't have faith that a movie showcasing villains would get traction at the box office.

3 BRYAN SINGER'S X-MEN 3

Bryan Singer X-Men

Director Bryan Singer's "X-Men" (2000) and "X2" (2003) were popular smashes, grossing $296.3 million and $407.7 million worldwide, respectively. The initial plan for "X-Men 3" called for shooting it concurrently with a fourth film. However, talks between Singer and Fox in 2004 for the third film stalled, and Singer was wooed away to direct "Superman Returns" for Warner Bros. Instead, Brett Ratner directed what became "X-Men: The Last Stand."

In an interview with Bleeding Cool, Singer said, "There are parts of 'X-Men 3' … it isn’t what I would have done, but parts of it, I liked. Ellen Page was something I liked in 'X-Men 3' and I’m bringing her to 'Days of Future Past.' Certain things are different. There was a lot going on in it and I wasn’t so happy with so many people dying, but then there were some really sweet moments with that kid, the cure kid." Singer did come back to the franchise, producing 2011's "X-Men: First Class" and directing 2014's "X-Men: Days of Future Past" and 2016's "X-Men: Apocalypse."

2 WONDER WOMAN

Wonder Woman

Joss Whedon, creator of "Buffy the Vampire Slayer," "Angel" and "Firefly," was slated to work his magic for a "Wonder Woman" film in 2005. Nearly two years of writing, however, didn't produce an approved script, so he was off the project by February 2007.

Whedon's take focused on the culture clash between Diana and Steve Trevor, in the film a humanitarian aid worker who crash-lands on Paradise Island. Whedon's Diana is a goddess unable to comprehend why humanity doesn't live up to its potential, but in Trevor's eyes, Diana's inability to understand human frailty makes her unable to truly be a hero. On his blog, Whedon tells what went wrong: "Let me stress first that everybody at the studio and Silver Pictures were cool and professional. We just saw different movies, and at the price range this kind of movie hangs in, that's never gonna work. Non-sympatico. It happens all the time." No worries: He went on to make "The Avengers" instead.

1 JUSTICE LEAGUE: MORTAL

Warner Bros. could have beaten Marvel Studios to the screen with its own film featuring its top heroes, but pulled the plug on "Justice League: Mortal" ahead of its slated 2009 release, three years before "The Avengers." In 2007, "Mad Max: Fury Road" director George Miller was assigned to the project, which had a script based on 2000's "JLA" "Tower of Babel" storyline (issues #43-46) by Mark Waid and Howard Porter, and the 2005 "infinite Crisis" tie-in "The OMAC Project" by Greg Rucka and Jesus Saiz. The script had Batman's files on other superheroes get hacked by Maxwell Lord, who triggers nanotechnology attacks on the League. The League then has to defeat an army of OMAC cyborgs deployed by Lord, as well as a berserk, mind-controlled Superman.

Several unknown and yet-to-be-famous actors such as Armie Hammer and Adam Brody were cast, and locations were scouted in Australia in early 2007, but the Writers' Guild of America went on strike, holding up production. After the strike ended, the script went in for polishing, but the tax incentives that brought production to Australia dried up, so Warner's killed the project. The documentary "George Miller's Justice League Mortal" tells the whole, frustrating tale.

Which of these movies did you want to see? Let us know in the comments!