Which films were on the brink of a completely different lead star?
With Robert Downey Jr fitting so perfectly as likeable irritant Tony Stark, Christian Bale slipping so easily into the tortured billionaire psyche of Bruce Wayne and Daniel Day-Lewis transforming himself into the epitome of Abraham Lincoln, it's hard to believe that for all of the above roles, there were some serious previous contenders. But contenders there were and some of the not entirely savoury.
Tom Cruise as Iron Man
The pint-sized action hero made it his mission impossible to kick ass as IMF agent, Ethan Hunt, but could he have romanced Pepper Potts in quite the same way as Robert Downey Jr's Iron Man? It seems like we very nearly found out with Cruise at one point in serious contention to play the arrogant but entertaining genius.
Tom Cruise could have been Tony Stark
Rumours circulated that Cruise was in line to take on the titular robotic character and his wealthy creator as long ago as the turn of the century. In 2004, Marvel Studios executive, Kevin Feige, was quoted as saying: "There have been discussion (with Cruise) over the last several years and there are a number of factors involved."
Are you pleased those factors couldn't be straightened out? Robert Downey Jr certainly must be.
Vanessa Williams as Leticia Musgrove in Monster's Ball
It was a defining moment in Halle Berry's career and in Academy Award history when the actress became the first, and, as of 2014, the only, woman of African-American descent to win an Oscar for Best Actress. But, had the casting calls gone the way producers of the film had originally wanted, the woman up on the stage receiving the award could have been entirely different.
Vanessa Williams may have robbed herself of an Oscar by not accepting the lead female in Monster's Ball
Vanessa Williams, star of Ugly Betty as scheming Wilhelmina Slater, was approached for the role and may have taken it under different circumstances. She told The Huffington Post: "I had just given birth ... I was like, 'I am not getting naked in front of a crew of people at this time!'"
Liam Neeson as Abraham Lincoln
Daniel Day-Lewis's impressive style of method acting cemented him as one of the most acclaimed actors of his generation, with his portrayal as Lincoln in the film of the same name giving him his third Academy Award in 2012. However, his record-breaking Oscar achievement - as the only male actor in history to receive three wins in the lead actor category - may never have come to fruition had Liam Neeson not stepped away from the role.
Liam Neeson could have been the Brit that stole the show as Abraham Lincoln
Neeson revealed that he had agreed to star in the Steven Spielberg biopic almost a decade ago, when the film was due to depict Lincoln's entire presidency instead of focus on the final four months of his life.
After a change in screenwriter and the unfortunate timing of a script reading just one month after his wife, Natasha Richardson, died, Neeson admitted defeat, decided the project just wasn't for him and told The Huffington Post: "I don't want to play this Lincoln. I can't be him."
Jake Gyllenhaal as Batman
Fresh from his dark and disturbed portrayal of the titular character in Donnie Darko, Gyllenhaal made it to the last eight possibilities for Christopher Nolan's turn at the Batman franchise.
Jake Gyllenhaal could have been The Batman
Rumours abound that he was the first choice for writer David S. Goyer before screen testing but Nolan pushed hard for Bale and got his wish, while Gyllenhaul could do nothing but look on as his sister Maggie got a turn in the second film of the trilogy.
Other potentials included Henry Cavill who may have been disappointed at the time of his Batman over-looking but later found superhero fame with the latest outing of Superman in Man of Steel.