The new Doctor is in, and she’s causing a lot of controversy.

Yes, “she.” Doctor Who will feature a female lead for the first time in the show’s 54-year history.

To date, the science fiction series has had 12 actors playing the role of the Doctor, a time-traveling alien capable of regenerating into different forms. English actor Jodie Whittaker will play the 13th version of the Doctor.

Whittaker is, of course, an accomplished actress. She graduated from the Guildhall School of Music and Drama in 2005, then performed in “The Storm” at Shakespeare’s Globe in London. She landed a major role in the BBC’s Broadchurch, a critically acclaimed drama that also starred Doctor Who alum David Tennant (the 10th Doctor). Whittaker’s other notable film roles include Venus, Attack the Block, and Adult Life Skills—all of which led to nominations for different film awards.

Whittaker will replace the 12th Doctor, Peter Capaldi, during the show’s 2017 Christmas special.

“I’m beyond excited to begin this epic journey – with [new showrunner] Chris [Chibnall] and with every Whovian on this planet,” Whittaker said in a statement. “It’s more than an honor to play the Doctor. It means remembering everyone I used to be, while stepping forward to embrace everything the Doctor stands for: hope. I can’t wait.”

For years, fans have speculated that the Doctor could regenerate as a woman. In the show’s canon, the Doctor is a Time Lord, a race of alien whose personality and physical characteristics change with every regeneration. Actor Matt Smith’s version of the Doctor made a reference to a possible female regeneration, so the move isn’t entirely unexpected.

Still, some fans reacted angrily to the announcement.

That’s perhaps understandable, since this seems, on its surface, like a major update. Whittaker urged Whovians to stay calm, noting that the Doctor has always changed with the times.

“This is a really exciting time, and Doctor Who represents everything that’s exciting about change,” she said. “The fans have lived through so many changes, and this is only a new, different one, not a fearful one.”

She added that she jumped at the chance to play one of the most iconic characters in science fiction.

“There was no persuasion needed,” Whittaker said. “If you need to be persuaded to do this part, you’re not right for this part, and the part isn’t right for you. I also think, for anyone taking this on, you have to want to fight for it, which I certainly had to do. I know there will have been some phenomenal actors who threw their hats in the ring.”

Other actors reportedly considered for the role included David Harewood, most famous in the U.S. for his role on Homeland, and Tilda Swinton, who starred in The Beach alongside Leonardo DiCaprio.

“Doctor Who” showrunner Steven Moffat will direct Capaldi’s last episode this winter.

Moffat will also leave the show in 2017, turning over the reins to Chris Chibnall.

Moffat says that Capaldi’s last episode will feature another Doctor—the very first Doctor.

“We’ve authentically re-created the First Doctor,” said Moffat of the episode. “We could put it out in black-and-white, and you would think it was William Hartnell [the actor who played the first Doctor]. There’s new monsters, there’s new jeopardy. But what’s fascinating is the First Doctor confronting the superhero he’s going to become, with his supersize TARDIS and all that.”

The episode will air on Dec. 25, 2017.