"Gravity" is currently raking in the cinema dollars. Alfonso Cuaron's space epic relies solely on the main actors' performances. Critics say that Sandra Bullock and George Clooney were perfect for their roles. But the cast would've been so different.

The original choices for the role of the trapped astronauts were Angelina Jolie and Robert Downey, Jr. "Tomb Raider" and "Iron Man" seemed to have more appeal with younger audiences, but they would have lacked the seasoned maturity for the complex roles. All's well that ends well.

Could we say the same for these original casting choices?

"Man of Steel" was down to True Blood hunk Joe Manganiello and Henry Cavill. Would it still be successful? How about Jessica Biel as Viper in "The Wolverine?" It went to relatively unknown Svetlana Khodchenkova. Also, the role of Khan was Benicio Del Toro's for the taking, but the price was steep.  Edgar Ramirez and Jordi Molla were among the names vying to replace him. Eventually, though, Abrams went in a different direction, hiring pasty Brit actor Benedict Cumberbatch to play the series role originated by Ricardo Montalban.

"The Butler" was a casting roller coaster by itself. The Vulture breaks it down: "John F. Kennedy proved hardest for director Lee Daniels to fill: When the project was first announced, Daniels had Hugh Jackman lined up to play JFK, with Mila Kunis as his Jackie. After both actors fell out, Daniels went after Matthew McConaughey and Minka Kelly to replace them, but McConaughey then departed to film Dallas Buyers Club, and Daniels scrambled to fill the presidential role with James Marsden, whom he happened to run into on the street a week and a half before the JFK scenes needed to be shot. That's not the only part Daniels had to recast: He originally wanted Liam Neeson to play Lyndon Johnson (a role that went to Liev Schreiber), was trying to lure Nicole Kidman to the movie for a never-specified role, and actually did cast Melissa Leo as Mamie Eisenhower, though her part was excised from the finished film."

Speaking of Hugh Jackman, he almost missed out on the lead role in one of his major movies this year. Nope, not "The Wolverine." (Seriously?) "Prisoners" was originally offered to director Bryan Singer (X-Men Days of Future Past) with Christian Bale and Mark Wahlberg for the roles that went to Hugh and Jake Gyllenhaal respectively.