Matt Smith has left, and Peter Capaldi is the new Doctor. Looking back on it now, I personally believe that Matt Smith was the most important of the new Doctors. Here are my 5 reasons why:
(Note: I originally published this article, with a few changes, on Yahoo!'s Contributor Network)
Some people will complain/disagree with this, but the fact is that while ratings have no true impact on whether a show is great or not (see "Firefly" or "Arrested Development" in the US for great shows that don't make it, and "Baywatch" or "American Idol" for crap shows that do) you need ratings to continue a show. Paul McGann, who could have been a truly great [Doctor Who](series:200668) (just go listen to the Big Finish audio plays sometime), couldn't get the ratings for his attempted reboot in 1996 in the US, leading to neither Fox nor Universal picking it up (it did quite well in the UK, with over 9 million viewers). Matt Smith's tenure however has led to "Doctor Who" getting its highest ratings ever in the US. Over 2.47 million watched the "The Time of the Doctor" alone, Matt Smith's final episode, giving BBC America its highest numbers ever.
Much like Peter Davison before him (the previous holder of "youngest actor to play the Doctor" at 29) Smith (26 when he took over) opened up the possibility that anyone could be the Doctor, not just an older person. Some people dislike Matt's "uncoordinated house-cat" routine (to borrow a popular quote), but it was refreshing. It brought Doctor Who just a little bit closer to my reality, as I am only two years younger than Smith. Just ask David Tennant what it was like watching a young Doctor as a kid.
Rather eloquently alluded to in "The Time of the Doctor", Matt Smith's 11th was a much needed re-set or reboot of the Doctor as a character. Eccleston and Tennant were essentially downers, living with the pain of the Time War (and the loss of Rose) almost to the exclusion of all else. Smith brought the Doctor back to the land of the living. He harkened back to the first Doctor, who simply stole a box and ran, more so than his predecessors did. This gives Peter Capaldi's upcoming 12th so much more room than Smith was left.
Eccleston was fantastic as a Doctor torn by his actions, living his life with the constant pain of what happened and wondering if it could have been different. You can see that he's a Doctor that is truly at a crossroads in his life, and isn't sure where to go. Tennant was brilliant as a Doctor who is beginning to heal, but can't quite get there. Still counting the deaths in his head, he learns that he can love again with the help of Rose Tyler, and maybe even forgive himself. But then Rose leaves, and as much as Martha Jones and Donna Noble try, they can't heal him. Tennant's 10th Doctor may not want to go, but he can't heal unless he does. Enter Smith's 11th. As revealed in "The Day of the Doctor", Smith has essentially "forgotten" the Time War and it's pain. He has come to accept it more so than his previous incarnations, and has decided to move on. He falls in love, gets married, and regains much of the vigor that he had had in the past (think 4th/5th Doctor). Now, with his memories of what really happened at the end of the Time War restored, it'll be interesting to see what the 12th will do.
What Smith leaves Capaldi is much greater than what Smith was left by his predecessors. Smith was able to take the character and redefine him (much like Tom Baker) and not only have him accepted (by most), but to actually have him loved. How many lists of "Favorite Doctor" does Tom Baker top? Nearly all of them. Smith will one day be near the top of those lists, if not holding the top spot itself. And not just from younger fans, but older fans as well. Smith is leaving Capaldi a show that is a hit in ratings (and was still moving up when he left), and a version of the Doctor that, love him or hate him, no one expects Capaldi to emulate in any way. This frees Capaldi, as a lot of the animosity towards Smith was that he wasn't Tennant. Smith's times includes a rich history, great quotes, memorable companions, and the most important thing he could leave to Capaldi: a nearly clean slate from which to forge a new path.