3. Giacomo Casanova Casanova
As everyone knows, David Tennant tried for the role of the Ninth Doctor back when Russell T. Davies was attempting to kick-start the moribund franchise out of its coffin and back into the primetime Saturday night slots. However, despite coming close, the role went to Christopher Eccleston, so Tennant went away, licked his wounds and came back as the Tenth. Yet what happened between those two events? Casanova, that's what. Released in April 2005 on BBC Three, Casanova followed the adventures of history's greatest lover as he shagged his way through 1700s Europe, and featured an astoundingly strong cast including Peter O'Toole, Rose Byrne and Rupert Penry-Jones. Yet still, the star of the show was Tennant, who despite O'Toole's best efforts, robustly refused to have the limelight stolen from him with a powerhouse performance. Sadly for Doctor Who fangirls who for some pre-Timelord sex scenes, there's not too much to go on here. Instead, we get a strangely poignant tale which requires Tennant to put in some real dramatic muscle. It's a bit jarring at first, but seeing the guy wrestling with his demons on a show which could've easily devolved into Carry On Venice proved strangely compelling viewing, and it's easy to see how Tennant landed one of TV's biggest roles off the back of this.