Comics have become ideal source material in Hollywood's eternal search for the next blockbuster. But in the numerous attempts to transform comic-book heroes into movie stars, some have, inevitably, failed in the making. I don't mean failed as in bad, but rather adaptations that were announced only to be canceled before moving into production. For today's "Six by 6," I look at six instances of movies that spiraled into an early grave, and commiserate over what could've been.

1. George Miller's Justice League: In 2007, Warner Bros. was hard at work developing a a feature based on DC Comics' top superhero team. In September 2007, the studio announced the hiring of director George Miller of Mad Max and Happy Feet fame, and pushed to get the film finished before the writers' strike.  The proposed budget clocked in at $220 million, with set already being constructed by early 2008 in Australia. Producers even went so far as casting Armie Hammer as Batman, Megan Gale as Wonder Woman, Common as Green Lantern and Adam Brody as the Flash, before the project was abruptly shelved. After the creation of DC Entertainment in 2009, this Justice League movie was permanently canned in favor of a new approach. I would love to have witnessed a movie like this. Miller is an excellent, and mind-bendingly diverse, director, and much of the movie would have relied on the strength of the script.

2. Doctor Strange by Guillermo del Toro and Neil Gaiman: Before Guillermo del Toro was as popular as he is now, he was actually signed on to develop a Doctor Strange movie in 2008, and even teased the idea of bringing on Neil Gaiman as screenwriter. The mere thought of that made most every fanboy salivate, but they were ultimately disappointed when the project never came together.

3. Darren Aronofsky's The Wolverine: Fox's follow-up to X-Men Origins: Wolverine is opening July 26, but initially it was going to be a far different film. When it was originally announced, avowed comic book fan Darren Aronofsky (Black Swan) was firmly in the director's chair with him on the same page with star Hugh Jackman to adapt Chris Claremont and Frank Miller's seminal Wolverine miniseries. Aronofsky ultimately bailed on the project early last year, leading the studio to hire James Mangold has his replacement. They're using the same source material and most of the same actors that Aronofsky's The Wolverine would have had, but it's still bittersweet to know what could have been.

4. Chris Columbus' Fantastic Four: Long before the 2005 Fantastic Four movie, acclaimed director Chris Columbus (Harry Potter, Home Alone, The Goonies) nabbed the FF film rights, and he worked on the project for years.Eventually he was pulled in other directions (namely, directing the first Harry Potter movie), but he still kept a hand in production and was one of the producers for what finally became 2005's Fantastic Four. It's an interesting game to speculate what that movie could have been had Columbus been on board for the casting, scripting and directing stages. Who knows, the gangsters from The Goonies do look an awful lot like something Jack Kirby would dream up.

5. Dazzler: The Movie: Believe it, true believers! It all started when '70s record label Casablanca approached Marvel about a unique venture in which they'd co-create a character that would be introduced in comics at the same time she debuted as the singer on an actual album. Marvel Editor-in-Chief Jim Shooter hurriedly wrote a script, which included a zany cast of characters such as the rock band KISS (which was signed to Casablanca at the time), Rodney Dangerfield in four roles (shades of Dr. Strangelove), Cher, and a then up-and-coming comedian named Robin Williams. That sounds similar to Tim Burton's Mars Attacks in terms of an on-screen spectacle, and I would have relished watching every minute of it.

6. Joss Whedon's Wonder Woman: Well before Joss Whedon directed one of the biggest movies of all time in Marvel's The Avengers, Warner Bros. had the enterprising director sewn up to write and direct an adaptation of DC Comics' to superheroine Wonder Woman. What could go wrong?  Everything, apparently. The suits at Warner Bros. apparently didn't like Whedon's outline, direction and who he envisioned as Wonder Woman (reportedly Cobie Smulders of The Avengers and How I Met Your Mother fame). At the time Whedon said a "lack of enthusiasm" led to the project never happening, but he'd return if the studio ever got serious about the project. I wonder if that offer still stands now after the success of The Avengers?