Since 2007, Warner Bros. has produced over two dozen direct-to-video animated movies featuring DC Comics characters, with three more ("Justice League Dark," "Teen Titans: The Judas Contract," and "Batman and Harley Quinn") on the way. Some have been original tales -- including the "Batman: Gotham Knight" anthology, the two Green Lantern movies and the alt-history "Justice League: Gods and Monsters" -- but the vast majority were inspired at least in part by pre-existing comics stories. While they vary in subject matter and (to a certain extent) in animation style and tone, for the most part they're not more than 90 minutes long and rated PG-13.

RELATED: The Best DC Comics Animated Series, Ranked

Of course, DC's characters have a long history in animation, going back to Max and Dave Fleischer's Superman cartoons of the 1940s. The "Timmverse" of animated series featuring Batman, Superman and the Justice League adapted its share of storylines, as did "Batman: The Brave and the Bold." Still, we suspect there are some stories the direct-to-video movies just won't tackle. They might be too long, too duplicative, too tonally different, or just too weird. In that spirit (and in no particular order) we offer ten DC stories which Warner Bros. could tell in animated form, but probably won't.

10 Sandman and/or Starman

Morpheus by Kieth and Dringenberg; Starmen by Andrew Robinson
Morpheus by Neil Gaiman, Sam Kieth and Mike Dringenberg from "Sandman" #1; and three Starmen from the cover of issue #79 by Andrew Robinson

"Sandman" ran 75 issues (1989-96), plus the occasional special issue and miniseries; while "Starman" racked up 83 (1994-2003) plus a handful of Annuals and other tie-ins. Each has become a quintessential part of DC's publishing history, not least because they focused largely on a single character, his unique supporting cast, his particular journey -- and that journey's end. Each also tied into DC's larger shared universe, with Morpheus fighting an amped-up Doctor Destiny and visiting Justice League International; and Jack Knight meeting a bevy of super-people before eventually joining the revived Justice Society. Adapting either of them into a series of direct-to-video animated movies would be a long-term investment Warner Bros. is probably unwilling to make. If it did, though, it might have a set of perennial video bestsellers, just like it does with the source material.

9 New Gods

Armagetto, by Jack Kirby
Darkseid in Armagetto, from Jack Kirby's "Hunger Dogs"

The great irony of "New Gods" is that its episodic structure builds to an epic confrontation which, due to external factors, fans never really got to see. (Walt Simonson's "Orion" series might have come the closest back in the early 2000s.) Jack Kirby conceived his saga as a limited series, but "New Gods" and "Forever People" were cancelled after 11 issues each, and "Mister Miracle" didn't last much longer. Moreover, a mid-1980s set of "New Gods" reprints included a new chapter designed to bridge the gap between the original series and 1985's "Hunger Dogs." That graphic novel was ostensibly Kirby's last word on the subject, but it was re-edited to be more open-ended so that DC could continue to use Darkseid and company. Indeed, the New Gods made some memorable appearances on the "Superman" and "Justice League" animated series.

We'd love to see Kirby's powerful stories translated into animation, and an animated movie (or series thereof) could go back to his original plan for "Hunger Dogs." It would never happen, though; because DC and Warner Bros. clearly want to keep the Fourth Worlders available for future movies. Regardless of how it was framed, an adaptation which showed the end of the saga would probably just confuse casual viewers.

8 Shazam!: The Monster Society of Evil

Shazam's cave, by Jeff Smith
The Seven Deadly Sins in Shazam's cave, from Jeff Smith's "Shazam! The Monster Society Of Evil"

Jeff Smith's back-to-basics take on Captain Marvel, Mary Marvel and the wizard Shazam remains a refreshing tonic for fans of the character's old-school setup. It blends the origins of Cap and Mary with an eerie, otherworldly menace; and it's got a great sense of humor to boot. While Smith's designs aren't all traditional, they're neither complicated nor overthought; which would translate very well to animation. It's also a good length for a direct-to-video movie.

Nevertheless, an adaptation would have to overcome some hurdles. First is Brie Larson's competing live-action "Captain Marvel" from Marvel Studios. Second, DC has spent the past several years (even before the New 52) rebranding Cap as "Shazam," complete with a new origin story from superstars Geoff Johns and Gary Frank. Additionally, Johns and Frank's Brainiac arc has already been adapted as the animated "Superman Unbound," so I suspect that makes it easier to market their Shazam story. (Plus, you know, Geoff Johns kinda runs a lot of things now.) Finally, Warner Bros. is still working on that "Shazam!" live-action movie starring Dwayne Johnson. All that means it's a lot less likely that Smith's version will be coming soon to video.

7 Supergirl: Cosmic Adventures in the Eighth Grade

Supergirl, by Eric Jones
Supergirl by Eric Jones, from "Cosmic Adventures in the Eighth Grade"

As the title suggests, this all-ages miniseries from Landry Walker and Eric Jones presents the Girl of Steel as somewhat younger than most other comics versions. Centered around Linda Lee's struggles to fit in at her boarding school, it still finds room for supervillains and world-shattering crises. When it debuted in late 2008, the main "Supergirl" title was only a few issues into what would be a well-received (and TV-influencing) run by Sterling Gates and Jamal Igle; and bad memories of previous missteps were still fresh in fans' minds. As with the "Monster Society," an animated version would definitely not be PG-13, but might be a less-frantic companion to "Teen Titans Go."

Ironically, that's part of why I don't think it would get made. An animated "Cosmic Adventures" might not be frantic enough to entice the "TT Go" audience, and it's clearly not adult enough to stand alongside the other PG-13 animated fare. Besides, it might be seen as too similar to the high-school-oriented "DC Super Hero Girls" cartoons; and/or too different from the "Supergirl" TV show. Like its title character, an animated "Cosmic Adventures" can't quite fit in.

6 'Mazing Man

'Mazing Man on Brave and the Bold
'Mazing Man, from "Batman: The Brave and the Bold"

Maze actually did get animated, in a very slapsticky episode late in the run of "Batman: The Brave and the Bold." However, the twelve issues and three specials' worth of "'Mazing Man" comics are more like a superhero sitcom -- or, to be more accurate, a sitcom starring a guy who wants to be a superhero and his dog-faced best friend. It was one of the sweetest, most heartfelt series to come out of DC's 1980s experimental period, and the publisher hasn't yet done anything quite like it.

Ideally, an animated "'Mazing Man" would just be a disc full of short stories exploring the everyday lives of Maze and company. It could even flirt with actual adult situations, because the comics didn't shy away from them. Otherwise, a "'Mazing Man" feature might turn out like "The Peanuts Movie," which had a main plot but digressed into various vignettes and subplots. Unfortunately, those structural concerns probably make it hard to sell. There's also the fact that -- Frank Miller "Dark Knight" cover notwithstanding -- it's still a rather obscure offering from three decades ago.

5 DC One Million

Justice Legion A
Justice Legion A, from "DC One Million" #1 by Grant Morrison and Val Semeiks

Other than Grant Morrison and Frank Quitely's "JLA: Earth 2" being adapted rather loosely into "Crisis On Two Earths," the Morrison-era JLA hasn't gotten a lot of animated attention. However, since it sought to bring back the widescreen-blockbuster feel to the Justice League's adventures, Morrison's run seems like pretty fertile ground. He and artist Howard Porter started with an invasion from an anti-League and ended with "World War III," and still found room for Darkseid to conquer Earth in the middle.

Perhaps there's no more Morrison-y arc than the line-wide crossover "DC One Million." Taking the conceit that DC will publish the 1,000,000th issue of "Action Comics" in November 85,271, "DC1M" has the 853rd Century's Justice Legion A travel back in time to fetch the "Prime Superman" and his League pals, because they're the guests of honor at a very special ceremony. The event miniseries finds Vandal Savage working both ends of the timestream, it's a prequel and a sequel to "All Star Superman," and its climactic moment is a fakeout executed almost flawlessly.

However, a couple of its big moments depend on Kyle Rayner and the Knight family of Starmen. While each was a staple of late-'90s DC, neither is especially prominent today, so each might require some time-sucking exposition from an animated adaptation. Additionally, because each Leaguer gets a solo mission in the future, a "DC1M" adaptation would have to find the right balance between following those adventures and staying focused on the main plot. It would probably benefit from being expanded into a two-parter, but Warner Bros. may not want to go that far.

4 Justice League International

Captain Atom and J'Onn J'Onzz share a moment, from Justice League International
Captain Atom and Martian Manhunter share a moment; from Keith Giffen, J.M. DeMatteis and Kevin Maguire's "Justice League International"

Sure, the main reason to animate "Justice League International" is its wackiness. Keith Giffen, J.M. DeMatteis and Kevin Maguire saw the comedic potential inherent in the World's Greatest Personality Clashes and ran with it, giving readers the immortal pairing of Blue Beetle and Booster Gold, the bomb-throwing Guy Gardner, the Oreo-fueled mellowness of J'onn J'onzz, and the frustrated professionalism of Batman and Black Canary.

Even so, the book's first twelve issues are a tale worth telling. Beginning with Max Lord secretly facilitating a terrorist attack on the United Nations, and ending with Max turning on his malevolent benefactor, they include fights with Russian super-operatives; the mystical menace of the Grey Man; an assault on the Manhunter homeworld; and (of course) Moving Day, as the League goes from simple super-team to globe-spanning peacekeepers. An animated adaptation could use Max's manipulations to tie all these vignettes together into a single narrative; and of course it would show the group coming together to honor its proud heritage.

The problem is that Warner Bros. tends to treat its Justice League features a lot more seriously; and it will probably continue to do so unless (and until) its live-action League is a success. Besides, you know what they say: widescreen action is easy, but comedy is hard.

3 Reign of the Supermen

Steel, the Cyborg Superman, Superboy and the Eradicator
Replacement Supermen: Steel by Jon Bogdanove and Dennis Janke; Cyborg Superman by Dan Jurgens and Brett Breeding; Superboy by Tom Grummett and Karl Kesel; Eradicator by Jackson Guice and Denis Rodier

This is kind of a cheat, because the first of these direct-to-video features was "Superman: Doomsday," featuring you-know-who's death and return. Indeed, that movie illustrates just how much a print story might have to change in order to fit into an animated version. Instead of four independent "replacements" and a plot to turn Earth into a planet-sized weapon, it had a Luthor-engineered clone. A more faithful adaptation of "Reign" could pick up with the aftermath of Superman's death; an overworked Supergirl; and the emergence of Steel, Superboy, the Cyborg Supes and the Eradicator. While the latter two were grounded rather deeply in the lore of then-current Superman comics, it wouldn't take long to explain them both as being "from space" -- in the sense that the Cyborg's consciousness was melded with baby Kal-El's ship, and the Eradicator is likewise an avatar from ancient Krypton. "Reign" starts out as a mystery, so a little exposition is going to be unavoidable.

Spanning twenty issues of the four Super-titles, and lasting throughout the summer of 1993, "Reign" allowed its various creative teams the room to give their heroes individual adventures before bringing them all together for the grand finale. An animated adaptation would most likely pare down subplots like Steel's fight with the White Rabbit or the Eradicator's love/hate relationship with Guy Gardner in order to get to the sudden but inevitable betrayal, and the big finish. After all, the question isn't whether Superman will return, but how big a splash it will make.

That, in turn, brings up the main reason Warners won't adapt "Reign": it's already working on bringing a live-action Supes back from the dead. Even though an animated "Reign" would necessarily come out well after "Justice League," why invite comparisons?

2 Green Lantern: Sector 2814

Green Lanterns of the '80s, by Dave Gibbons and Howard Chaykin
Green Lanterns in the mid-'80s: Hal Jordan and John Stewart by Dave Gibbons and Guy Gardner by Howard Chaykin

In 1984, Hal Jordan's quitting the Green Lantern Corps kicked off an 18-issue arc (collected in the "Sector 2814" trade paperbacks), during which John Stewart settled in as Earth's GL and Guy Gardner emerged from a years-long coma. After Hal quit, he took on a slightly pathetic air, hanging around Coast City without much to do. Meanwhile, John was being trained by Katma Tui and Guy was making up for lost time. When all was said and done Hal was back, John's position was secure, Guy was eager to make his mark; and the Guardians were ready to step back for a while. More importantly, by promoting John and Guy the arc presented them all as equals and helped establish today's relationships.

An adaptation could pick up with 1985's "Crisis on Infinite Earths" crossovers (substituting a comparable cosmic threat, of course), because that's when the Guardians' infighting intensified. The adaptation would then show each of the heroes becoming a proxy for a different faction. While there's spectacle, the story's strength is in its characters. Still, at this point it might be too insular; and it may require too much backstory to be adapted efficiently.

And finally...

1 Batman: Strange Apparitions

Batman versus the Penguin and Deadshot, by Marshall Rogers
Detail from the wraparound cover of "Shadow of the Batman" #3, reprinting two issues by Steve Englehart, Marshall Rogers and Terry Austin

Steve Englehart's eight issues on "Detective Comics" in the mid-1970s helped set a new standard for Batman arcs. The first two (drawn by the team of Walt Simonson and Al Milgrom) introduced corrupt councilman Rupert Thorne and businesswoman Silver St. Cloud, but the next six (drawn by Marshall Rogers and Terry Austin) kicked the story into another gear. Englehart, Rogers and Austin reintroduced and redefined Hugo Strange and Deadshot; made Batman and Robin outlaws; gave Bruce Wayne a romance for the ages; and produced one of the all-time classic Joker stories.

In fact, this run inspired an unproduced "Batman" movie from screenwriter Tom Mankiewicz; it influenced 1989's "Batman" (specifically Vicki Vale's character); and "Batman: The Animated Series" adapted "The Laughing Fish." Those are good reasons why viewers may never see a straight-up adaptation of Englehart, Rogers and Simonson's work; which is both good and bad. The arc practically cries out to be animated in full, but at the same time the comics are so good that an adaptation would just be gravy.

What DC Comics story needs the animated treatment but almost certainly won't get its own movie? Let us know in the comments!