Having served under Matt Smith and Peter Capaldi's Doctors, including key roles in the 50th anniversary, she is currently the longest serving companion of the modern era, and will likely be looking to use her role on the iconic show to build a career.
Clara (Jenna Coleman) and The Doctor (Peter Capaldi).
The role of companion used to be more of a curse than a blessing when it came to career success. During the show's original 26-year run, the actresses who came on board the Tardis struggled to find work due to being typecast.
Original companion Carole Ann Ford described in 2013 how the show ended her acting career as people only wanted to see her in parts similar to her role as Susan Foreman.
However, since the show's reboot in 2005, Doctor Who has proved a launching pad for many a young British star. Here's a brief look at just what the Doctor's crew has gotten up to since leaving the show, which may provide comfort for Coleman as she leaves behind her part in one of the biggest shows on the planet.
Billie Piper
Character name: Rose Tyler Tardis Tenure: 2005-6, recurring 2008. Notable moment: Looked into the heart of the Tardis, briefly giving her the power to rewrite the universe and crafting the name 'Bad Wolf'. Demise: Became trapped in a parallel dimension whilst trying to stop the Daleks.
David Tennant as the Doctor, and Billie Piper as Rose in the television series Doctor Who.
Post Who: Originally a pop star pre-Who, Piper used her time as Rose to propel herself into a successful acting career. While most notable for her four seasons as the lead of Diary of a Call Girl, Piper has had several theatre roles and currently stars in horror series Penny Dreadful. She had a small role in Who's fiftieth anniversary reprising the Bad Wolf side of her character, as well as a cameo in David Tennant's last episode as Doctor.
Character name: Captain Jack Harkness Tardis Tenure: 2005, recurring 2007-8. Notable moment: First recurring openly bisexual character on Doctor Who. Also immortal after being brought back from the dead, which is fairly handy. Demise: Was killed by the Daleks but brought back to life by Rose, yet left behind by The Doctor
Actor John Barrowman.
Post Who: The charismatic, American accented Barrowman quickly turned Harkness into a fan favourite, and he has carved a varied career out of that popularity. He was chosen as the lead of Doctor Who spinoff Torchwood¸ which he led for four seasons, and currently recurs on Arrow as the antagonist Malcolm Meryln. Outside of acting, Barrowman is a successful singer and performer, having recorded a number of albums and performed in various musicals and theatre productions. He and his sister Carole have also co-authored several books together.
Freema Agyeman
Character name: Martha Jones Tardis Tenure: 2007, recurring 2008. Notable moment: Travels for a year alone through a dystopian Earth spreading the story of the Doctor Demise: Amicably parts ways with the Doctor after accepting he won't return her love for him.
The Doctor (David Tennant) with Martha (Freema Agyeman).
Post Who: Agyeman originally left Who for spin-off Torchwood, where she had a brief role in the second season. The actress then went on to co-star in Law and Order: UK for six seasons (British seasons though, so only 39 episodes) before leaving for a recurring role on Sex and the City prequel The Carrie Diaries. Most recently, Agyeman was part of the Netflix sci-fi drama Sense8.
Catherine Tate
Character name: Donna Noble Tardis Tenure: 2008, plus 2006 and 2009 Christmas specials . Notable moment: Absorbed part of the Doctor's DNA while accidentally cloning him from his amputated hand (it's a long story). Demise: Has her memories wiped by the Doctor .
Actress Catherine Tate. Photo / Getty Images
Post Who: Tate had a successful career as a comedian pre-Who. She had become a household name in the UK through her self-titled sketch show, crafting memorable characters such as Lauren Cooper and Nan Taylor and starring in Comic Relief sketches alongside Daniel Craig and Tony Blair. Since Who, Tate has had small roles in movies Gulliver's Travels and Monte Carlo, and co-lead alongside David Walliams in the comedy Big School. Her biggest role was a recurring part in the final season of the American Office, but she has also built up a prolific theatre career, including co-starring with David Tennant in a 2011 adaptation of Much Ado About Nothing.
Arthur Darvill
Character name: Rory Williams TARDIS Tenure: 2010-12 Notable moment: After being thought dead, Rory came back as an Auton (plastic robots), and spent two thousand years guarding his fiancée Amy (it's a longer story than the hand-clone). Demise: Lives out his days in early 20th century New York after being sent back in time by the Weeping Angels.
Actor Arthur Darvill. Photo / Getty Images
Post Who: Darvill is most notable so far for his small role as the Reverend Paul in Broadchurch. He also spent a year on Broadway as one of the leads of musical Once. He will likely come to more attention next year as part of the Arrow/Flash spinoff/crossover Legends of Tomorrow, playing DC Comics time traveller Rip Hunter.
Karen Gillan
Character name: Amy Pond Tardis Tenure: 2010-12 Notable moment: First companion to become pregnant. Amy eventually gives birth to half-Time Lord daughter Melody, who grows up to become the Doctor's eventual wife and would be assassin River Song (really, the amputated hand-clone storyline is a breeze compared to this). Demise: Willing lives out her days in early 20th century New York after her husband Rory is sent back in time.
Actress Karen Gillan.
Post Who: Gillan has probably had the most high profile career since leaving Who. After starring in a few indie movies, including low-budget horror Oculus, Gillan led American comedy Selfie for one season before it got cancelled. She famously shaved her head to play Nebula in Guardians of the Galaxy, and will reprise the role in the superhero sequel. She recently filmed an HBO pilot about the Salem witch trials, is part of the cast of Brad Pitt's next movie The Big Short and is currently filming The Circle alongside Tom Hanks and Emma Watson. Despite her busy schedule, she squeezed in a brief cameo during Matt Smith's final episode as The Doctor in the 2013 Christmas special.