Sisto first appears around the 0:30 minute mark in the above video, playing Jack opposite a vibrant Kate Winslet, then 19 years old, during her "Titanic" screen test for the role of Rose DeWitt Bukater. With Sisto's awkward, fidgety portrayal, it's easy to see why the soulful-eyed Leonardo DiCaprio ultimately snagged the coveted role.
Since actors in Hollywood's most iconic roles bring much of their own personality and style to their characters, it can be difficult to imagine anyone else playing them. What if somebody else had played Hans Solo? Indiana Jones? Scarlet O'Hara? In the following list, we look at famous castings that could have been.
Tom Selleck -- Indiana Jones
Moustachioed actor Tom Selleck, who turned down the role of the world's most famous archaeologist to star in "Magnum P.I.," has reportedly been "haunted" by the decision ever since. Here's his screen test for "Raiders of the Lost Ark," a performance which creator George Lucas called "really, really good."
Kurt Russell, Christopher Walken -- Han Solo
Several actors were considered for the role of "Star Wars'" swashbuckling smuggler, Han Solo, including Al Pacino and Nick Nolte. Here's Kurt Russell's nice-boy take on the famous hero.
Another rumored pick was Christopher Walken. Though it never came to pass, fellow actor Kevin Spacey can give us some idea of what it might have looked like.
Katie Holmes -- Buffy Summers
Katie Holmes turned down one of television's greatest female characters, Buffy Summers, to finish her final year of high school. Joss Whedon ultimately chose Sarah Michelle Gellar, originally cast as shallow sidekick Cordelia, to slay the vampires of Sunnydale.
Bette Davis -- Scarlett O'Hara
Though Bette Davis campaigned to play Southern belle Scartlett in "Gone with the Wind," she lost out to unknown actress Vivian Leigh. But she still got the chance to wear hoop skirts in 1938's "Jezebel," for which she won an Oscar.
Will Smith -- Neo
Will Smith could have been "The One," but when he chose "Wild Wild West" instead, Keanu Reeves got the part. In an interview with Wired, Will Smith admitted that he "would have absolutely messed up 'The Matrix.'"
"At that point I wasn’t smart enough as an actor to let the movie be—whereas Keanu was," he said.
Eric Stoltz -- Marty McFly
Originally cast as "Back to the Future's" skateboarding time-traveler Marty McFly, Stoltz lost the part five weeks into shooting, after producer Steven Spielberg and director Robert Zemeckis decided the actor didn't bring the right amount of humor to the role. The part of McFly went, obviously, to Michael J. Fox.
Sean Connery -- Gandalf
Sean Connery could have played wise old wizard, Gandalf, of J.R.R. Tolkien's "Lord of the Rings" trilogy, but the Scottish actor turned it down because he "didn't understand the script."