Jake Gyllenhaal in Prince of Persia: The Sands of TimeIn 'Prince of Persia: The Sands of Time,' the lovable Jake Gyllenhaal steps up to summer blockbuster plate as the heroic Prince Dastan, appearing bulked-up and ready to take down bad guys on ancient turf. But the affable star isn't the first to radically change his physique for a part. As 'Persia' gallops into theaters, we took a look at some of Hollywood's most iconic actors whose roles have called for dramatic physical transformations.