Paul Shaffer – Seinfeld
Paul Shaffer, who’s best known for serving as David Letterman’s musical director, band leader, and sidekick on Late Night with David Letterman as well as Late Show with David Letterman admitted that he nearly starred in Seinfeld as George Costanza. He turned down the role saying that he was just too busy playing music, not realizing that it would become one of the most successful TV shows of all time.
Tom Hanks – Jerry McGuire
At first, director Cameron Crowe approach Tom Hanks to play the role of Jerry McGuire. However, he turned down the role as he was busy directing the film That Thing You Do. Tom Cruise ended up taking the role instead, and Hanks admitted that he thought nobody else could play Jerry McGuire other than Cruise.