4. David Tennant Is... The Ninth Doctor! (2003)
With Grant turning down the role, casting director Andy Pryor drew up a long-list of possible Doctors for Davies and the BBC Wales production team. Briefly flirted with was a young, respected radio and theatrical actor from Scotland called David Tennant, who some years before had narrowly missed out on the lead role of Tom Quinn in Spooks. Tennant was ruled out as having too-little TV experience and too-small profile at the time, but in 2004 found himself cast in Casanova, also scripted by Davies, which gave him his break-out role and a bigger TV profile, just at the right time, the very next year...