Because Doctor Who has been running for such a long time, it's quite common for actors to have multiple opportunities to land a part in the show.
An actor might audition for a certain role in the early stages of their career, only to lose out due to lack of experience. But then, 30 years later - when Doctor Who is still going - they might read for a different part entirely, and go on to win it.
Double-dipping is extremely common in the Doctor Who world, and while some actors do manage to snag multiple roles in the show, countless others are not as successful, and there are many performers in the Whoniverse who have also been linked with different characters over the years, but for whatever reason, these didn't work out.
There's an alternate reality out there where the following actors either managed to land two roles in the show, or a different role than the one they ended up getting. As it stands though, they all got close - but not close enough - to playing other characters in Doctor Who, from major leading roles, to smaller supporting cameos.
10. Russell Tovey
Who He Almost Played: The Eleventh Doctor
Who He Actually Played: Alonso Frame
As midshipman Alonso Frame in the 2007 Christmas special Voyage Of The Damned, Russell Tovey provided David Tennant's Tenth Doctor with one of his most memorable moments, allowing the Time Lord to finally use the phrase "allons-y, Alonso!" in front of someone who is actually called Alonso.
This aside though, Tovey didn't really get many standout moments in the episode, but the character he almost played would've given him standout moments galore.
During a chat with The Independent in April 2013, Tovey spoke about how he was in the running to play the Eleventh Doctor, a role that, of course, eventually went to Matt Smith. Reportedly, Tovey got so close to bagging the part that he was even screen-tested for it, but from the sounds of it, he's glad he missed out:
“It would have terrified me. I don’t know what I would have done with all the attention.”
Voyage Of The Damned aside, Tovey also played Alonso in a quick cameo during The End Of Time, where he hooked up with Captain Jack Harkness after the Doctor set them up. Top wingman.