1. Kate Winslet
Russell T. Davies had given Kate Winslet her big break when it came to television in his 1991 teen drama series Dark Season. The fact that she had become a major film star in the years since did not deter him from pursuing her for the role of Professor River Song. Either she or her agent turned the part down and ERs Alex Kingston was cast. This is possibly the most intriguing what if casting on this list. Since River Song became a recurring character, one cant help but wonder if Winslet wouldve taken time off from her movie career to play the Doctors wife. While Kingston made the role her own, the Doctor couldve done a lot worse than marry an Oscar winner.