Is this the face of the 12th Doctor?
“I would like to play the new female Doctor Who," said Mirren. "I don’t want to just be his sidekick.”
Without context, it's not clear if Mirren was serious or joking when she made that comment. But it's not entirely out of the question for the next Doctor to be a woman. During the Neil Gaiman scripted episode "The Doctor's Wife," it was established that a Time Lord named The Corsair became a woman (or a Time Lady) during some of his regenerations. And if The Corsair could do it, then it could potentially happen to The Doctor as well.
There are also ongoing rumors that the upcoming seventh season of the revived "Doctor Who" will be the last for the current Doctor, Matt Smith. The sixth season finale set up a future storyline based around an event called "The Fall of the Eleventh;" which suggests that it's an early setup for what could be Smith's final story in the iconic role. The Doctor's companions Amy Pond (Karen Gillian) and Rory Williams (Arthur Darvill) are already slated to leave the series sometime in the next season; which only adds fuel to the rumors about Smith.
Mirren is best known in the U.S. for her roles in "Red" (pictured above), "The Debt," "The Last Station," "Gosford Park," "National Treasure 2: Book of Secrets," "State of Play" and several other films. However, she also originated the role of Detective Jane Tennison in "Prime Suspect" and portrayed both Queen Elizabeths in "Elizabeth 1" and "The Queen," respectively.
Although Mirren has the star power to step into the role of the Doctor, her age would probably be the only thing working against her if Mirren truly wants the role. Mirren is 66 years old while the current Doctor is played by the 26 year old Smith. While Mirren's hypothetical casting would buck the trend of casting younger and younger Doctors, it doesn't seem very likely.
However, speaking as a "Doctor Who" fan, I would love to see Mirren take a role on the show. And if that means taking a brief stint as the Doctor, then why not?
Feel free to weigh in with your own opinions in the comment section below!