7. Dennis Hopper
Veteran character actor Dennis Hopper expressed interest in a Doctor Who guest spot in early 2007. As chronicled in Russell T. Davies behind-the-scenes book The Writers Tale, the production team had hoped he would appear in that years Christmas special Voyage of the Damned either as the tour guide Mr. Copper or the villain Max Capricorn. But negotiations stalled and Clive Swift and George Costigan were cast instead. American actors in Doctor Who are few and far between and getting the Oscar-nominated Hopper would have been quite a coup. Of course, he would have stuck out like a sore thumb amid all the British accents.