Lost

Jon Hamm auditioned for the role of Jack Shephard.

The only member of the principal cast who didn't have to audition for a role was Terry O'Quinn, with whom J.J. Abrams had previously worked on the second season of 'Alias'.

Originally, Michael Keaton was cast as Jack. In the first draft of the script Jack was to be killed by the monster after they arrived at the cockpit. ABC told the producers that they shouldn't kill off the hero so soon in the series and the script was changed. After the change, Michael Keaton backed out of the role since he did not want to commit to a regular series.