Acting can be an incredibly fickle business. When a star agrees to take on a role, they are none the wiser as to whether the movie will be a flop, a success, or even a cult classic. Any decision - be it affirmative or a rejection - may go on to haunt the actor forever. Potentially, the actor in question might find their career plagued by thoughts of "what if".

Related: 10 Actors Who Stormed Off Set

There are many iconic roles that have been turned down by A-listers. We cannot help but wonder how these movies would have turned out had the original casting choices said yes. Keep reading to find out which iconic roles these A-list stars rejected.

10 Will Smith - Neo ('The Matrix')

The Matrix remains one of the most popular and highest grossing movie franchises of all time. But the iconic character of Neo, perfectly brought to life by Keanu Reeves, could have gone to a decidedly different star.

Related: Will Smith Just Made Dad Bods Cool And Trendy

None other than Will Smith was initially offered the role of Neo, but he rejected it. On his YouTube channel, he explained that he didn't like the Wachowskis' description of the movie and ended up starring in a major flop, Wild, Wild West, instead.

9 John Travolta - Forrest Gump ('Forrest Gump')

We can't possibly imagine the titular hero of Forrest Gump played by anyone other than Tom Hanks. But it turns out that the part was originally offered to John Travolta, who rejected it so he could star in Pulp Fiction instead.

Forrest Gump was a colossal hit at the box office, but it has aged quite badly and is now considered problematic both for its depiction of disability and its treatment of love interest Jenny. For this reason, we think it's a wise decision that John Travolta turned it down in favor of the enduringly popular Pulp Fiction.

8 Emily Blunt - Black Widow ('Iron Man 2')

The Marvel Cinematic Universe boasts a colorful and varied array of actors, with many Brits enjoying success thanks to the immensely popular superhero movies. It makes sense, then, that British actress Emily Blunt was offered the role of Black Widow in Iron Man 2. But it wasn't to be, as the scheduling conflicted with her role in the 2010 adaptation of Gulliver's Travels.

The role then went to Scarlett Johansson, who has immortalized the iconic character. Blunt has said that she doesn't regret turning down the part, as she's not too keen on Marvel's depiction of women.

7 Gwyneth Paltrow - Rose ('Titanic')

Is there a movie image more iconic than that of Kate Winslet and Leonardo DiCaprio embracing on the eponymous ship in Titanic? Well, the lady that Leo embraces could very well have been Gwyneth Paltrow. To this day, Paltrow says she regrets having turned down the role, telling Howard Stern, "I look back on the choices I've made and think, 'Why the hell did I say yes to that? And no to that?'"

Kate Winslet has since expressed her regret and discontentment at her famous nude scene in the movie, so perhaps Gwen can look at it as not such a big loss after all.

6 Matt Damon - Ennis Del Mar ('Brokeback Mountain')

The soulful Ennis Del Mar was perfectly embodied by the late Heath Ledger in cowboy romance Brokeback Mountain. But Matt Damon was the first choice for the classic role. Initially, Gus Van Sant was at the helm as director and Damon's reasoning for rejecting the role is a little un-PC.

"I was like, 'Gus, I'm going to do a gay movie, then a cowboy movie. I can't follow it up with a gay-cowboy movie!" he laughed in a 2007 Entertainment Weekly interview. That's actually not the first time Damon has been problematic, though he did add that he ultimately regretted turning down the part.

5 Christina Applegate - Elle Woods ('Legally Blonde')

Reese Witherspoon was the perfect choice for the bubbly but intelligent lawyer Elle Woods in the Legally Blonde movies. Initially, Christina Applegate was offered the role, but she passed on it.

She told Andy Cohen that she doesn't regret it "because Reese Witherspoon did a much better job". Interestingly, Applegate auditioned for another classic movie role that features in this list: Rose in Titanic.

4 Michael Caine - Bob Rusk ('Frenzy')

1972 horror-thriller Frenzy is notable as being both the first movie Alfred Hitchcock had directed in Britain since 1950 and as being famously graphic in its depictions of violence, whereas earlier Hitchcock movies had only alluded to sadism.

For the role of despicable serial killer Bob Rusk, Hitchcock's first choice was Michael Caine. However, Caine was repulsed by the character and didn't want to be associated with him. Subsequently, the lesser known Barry Foster was cast.

3 Daniel Day Lewis - Oskar Schindler ('Schindler's List)

Steven Spielberg's harrowing Oscar-winning drama Schindler's List starred many Brits and one British A-lister in particular was offered the title role. Daniel Day Lewis rejected the part of Oskar Schindler because he wasn't keen on working with Spielberg, who had taken over directing duties from Martin Scorsese, Day Lewis' friend.

The role went to Liam Neeson, in his pre-action star days, and we think he was the ideal candidate for the part.

2 Hugh Jackman - James Bond ('Casino Royale')

That's right: everyone's favorite friendly Aussie and "Nicest Guy in Hollywood" was actually asked to play James Bond. But Hugh Jackman turned down the iconic role. As he explained to Variety, "I just felt at the time that the scripts had become so unbelievable and crazy, and I felt like they needed to become grittier and real... I was also worried that between Bond and X-Men, I'd never have time to do different things."

Related: How Did Hugh Jackman Meet His Wife Of 25 Years, Deborra-Lee Furness?

Of course, the role eventually went to Daniel Craig, who has been a monumental success as Bond, but considering how well Jackman has done in the MCU we doubt he regrets his decision too much.

1 Emma Watson - Mia Dolan ('La La Land')

For so many Harry Potter fans, Emma Watson will always be Hermione Granger. But she had a real opportunity to branch out into other acclaimed roles with an offer to star as Mia Dolan, the female lead in La La Land. However, Watson declined because she didn't have the time to devote herself to the role, having been extremely busy filming Beauty and the Beast. 

Considering the notorious Oscars faux pas in which the movie was erroneously declared the Best Picture winner, Watson probably saved herself some embarrassment.

Next: 10 Actors Who Don't Even Watch Their Own Movies