Matt Damon - Avatar
Titanic was the highest grossing film of all time, until Avatar came out in 2009 which proved that James Cameron really knows how to turn out a Blockbuster hit.
Matt Damon was Cameron's first choice to play Jake Sully in the blue alien blockbuster. But having other film commitments at the time, Damon was unable to accept the role.
"I particularly wanted to work with James Cameron, and still do… He knew he was the star of that movie and that everyone was going to see it anyway," Damon said in a 2012 interview.
"When he said, ‘Look, I’m offering it to you, but if you say no, the movie doesn’t need you,’ I remember thinking, ‘Oh God, not only do I have to say no because of scheduling, but he’s going to make a star out of some guy who’s going to to start taking jobs from me later,' Damon said.
That's when Australian actor Sam Worthington stepped into the role and shot to stardom.
Leonardo DiCaprio- American Psycho
There are very few actors that can pull off a role refined yet maniacal psychopath with such precision, and Christian Bale is one of them.
The lead of Wall Street banker Patrick Batemen in 2000 flick American Psycho almost didn't go to him, however. With Leonardo DiCaprio's popularity after the box office smash hit of Titantic he was the natural pick for the role.
Bale was so confident that DiCaprio would drop out from the movie that he didn't take any roles for nine months.
After disputes with the movie's director, Oliver Stone, DiCaprio indeed did drop out and Bale landed the role he was promised, which propelled him to fame.
Years later DiCaprio would end up playing another financier character in the 2014 hit Wolf of Wallstreet.
John Travolta- Forrest Gump
Known for it's memorable quotes and touching story, this classic movie almost didn't have Tom Hanks as the lead role. John Travolta was actually in the running to play the titular part in the 1994 flick.
Travolta, however, declined the part for unknown reasons. He has since expressed regret about not taking the role which earned Tom Hanks his second Oscar for Best Actor. Hanks is the only person in history to have won the Best Actor Oscar two years in a row.
Source: Daily Mail