Jenna Coleman will leave 'Doctor Who' at Christmas.
The actress has played the Time Lord's companion Clara Oswald since her debut episode 'Asylum of the Daleks' aired in September 2012, and it is said she has agreed with bosses that an exit later this year will be right for the science fiction show.
An insider told the Sunday Mirror newspaper: "The conversations about Jenna's exit have started, and a plan is in place which is being ironed out.
"By the time she leaves she will be one of the longest-standing companions ever. She has been absolutely brilliant in the role but everyone agrees it is a part that should change after a period."
The decision to end Jenna's time on the show is said to have been "mutual", and all parties feel it will be "perfect" for a Christmas storyline.
The source added: "It was very much a mutual decision. It's important to keep the series moving and fast-paced, and the time is just starting to feel right and the feeling is that it could be a perfect Christmas storyline."
Meanwhile, the star has insisted she isn't thinking about "the future" and wants to simply "enjoy" her time on the show.
She told The Independent on Sunday newspaper's New Review magazine: "At the moment I'm really happy.
"It's one of those jobs that will only happen once - the whole adventure that it brings. The key is not to worry about the future, and enjoy it."