Jake almost was Sully in Avatar? What would you all have thought? A good fit, but Sam Worthington has also done a great job.
"Avatar is well on its way to being one of the biggest movies of all time, and it’s doing it without major A-list star power. Instead the movie’s leading roles are played by up and comers in Zoe Saldana and Sam Worthington. It could have turned out differently. James Cameron tells MTV that the role of Jake Sully almost went to Jake Gyllenhaal or Matt Damon."
Source: Josh Tyler,
cinemablend.com