Swann
Christopher Reeve came back into Superman’s world a final time before his untimely death. Reeve portrayed Dr. Virgil Swann in two episodes during the second and third seasons. Moreover his sidekick Lois Lane, AKA Margot Kidder, also joined the cast for a few episodes.
Chloe Sullivan
Kristen Bell, who went on to play the iconic Veronica Mars, auditioned for the part of Chloe Sullivan before Allison Mack was cast in the role. Hmm, either way, it would have been a win-win. Especially considering Mack’s scandal right now, but more on that later.