‘Doctor Who’ Season 10: Matt Smith Replacing Peter Capaldi In Season 12? Twelfth Doctor Regenerating Back To Eleven?

"Doctor Who" fans know that there's nothing constant about the long-running series' casting. The Doctor's looks and personality change every now and then thanks to his regeneration abilities, and his companions leave his side for different reasons.

Peter Capaldi is the latest actor to don the Doctor persona. But there are rumors circulating around that the next incarnation of the iconic role will go back to another actor who played it in the past -- Matt Smith, the Eleventh Doctor.

Matt Smith Misses 'Doctor Who'

Current "Doctor Who" showrunner Steven Moffat said Smith is "quite open about how he misses" playing the Doctor and "how much he wishes he hadn't left," The Mirror reported. Moffat also recounted about the time Smith finally decided to depart the series three years ago, which he described as a "tough time" that "felt like everything was blowing up" around him.

According to Moffat, he couldn't convince Smith to stay as the Eleventh Doctor back then. The 32-year-old actor played the role from 2009 to 2013 and has since appeared in a bunch of other projects including "Terminator Genisys."

Back in April, Smith expressed that he wants to play the Doctor again. He also said in another interview that he somewhat expects "Doctor Who" execs to ask for him back, the news outlet added.

However, Moffat's recent comments do not necessarily mean that Smith would reprise his Eleventh Doctor role. If the actor does come back, it could be in the form of a flashback, or as another character that resembles the Doctor's 11^th incarnation.

There's also a possibility that Smith would return as a guest star in an episode that will feature multiple Doctors, much like what happened when the show's 50^th anniversary featured both the Tenth Doctor (David Tennant) and Eleven. It could be the last hurrah of Capaldi and Moffat before they leave "Doctor Who."

Peter Capaldi & Steven Moffat's Departure

Moffat announced in January 2016 that he will be stepping down as "Doctor Who's" showrunner when season 10 wraps, Screen Rant reported. His role will be filled by Chris Chibnall.

Capaldi, meanwhile, is speculated to leave "Doctor Who" after season 10. The 58-year-old actor, however, said in an interview with RadioTimes that he was being asked to stay until season 11. Capaldi said he's yet to decide about the matter, though he admits that saying goodbye to the show will be "very difficult."

"Doctor Who" Season 10 will air in spring 2017, with Pearl Mackie as the new companion Bill. The Doctor, however, will have "a different, guest companion" in this year's Christmas special, an annual tradition of the show since it was relaunched in 2005, Screen Rant noted.