A general view of the atmosphere at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Mediator Craig Ferguson speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Mediator Craig Ferguson speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Actor David Bradley speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Actress Jenna Coleman speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Actor Matt Smith speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Actor Matt Smith speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Actor Matt Smith speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Mediator Craig Ferguson (L) and actor Matt Smith speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Mediator Craig Ferguson, actors Matt Smith, and Jenna Coleman speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Actors Matt Smith (L) and Jenna Coleman speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

A general view of the atmosphere at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Actor Matt Smith speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Actor Matt Smith speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Jenna Coleman speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Jenna Coleman speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Writer Steven Moffat speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

David Bradley speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Actor Matt Smith speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Actors Matt Smith (L) and Jenna Coleman speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

 Actress Jenna Coleman speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Writer Steven Moffat speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

 A general view of the atmosphere at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Actress Jenna Coleman (L) and writer Steven Moffat speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

 Producer Marcus Wilson speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

(L-R) Actors Matt Smith, Jenna Coleman, writer Steven Moffat, David Bradley, Mark Gatiss, and Marcus Wilson speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

 Mark Gatiss speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Mark Gatiss (L) and Marcus Wilson speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

(L-R) Actors Matt Smith, writer Steven Moffat, David Bradley, Mark Gatiss, and Marcus Wilson speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

(L-R) Steven Moffat, David Bradley, Mark Gatiss, and Marcus Wilson speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

(L-R) Mediator Craig Ferguson, actors Matt Smith, Jenna Coleman, writer Steven Moffat, David Bradley, Mark Gatiss, and Marcus Wilson speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Kevin Winter/Getty Images)

Actor Matt Smith speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Actress Jenna Coleman speaks onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

(L-R) Actor Mark Gatiss, actor David Bradley, actor Matt Smith, actress Jenna Coleman, producer Marcus Wilson, and writer Steven Moffat speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

(L-R) Actors David Bradley, Jenna Coleman, and Matt Smith speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Actors David Bradley (L) and Matt Smith speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)

Actors David Bradley (L) and Matt Smith speak onstage at BBC America's "Doctor Who" 50th Anniversary panel during Comic-Con International 2013 at San Diego Convention Center on July 21, 2013 in San Diego, California. (Photo by Albert L. Ortega/Getty Images)