Why Every Modern Companion Left Doctor Who

Story reasons for a Doctor Who companion exit can vary from being trapped in an alternate reality to getting sent back in time by a Weeping Angel, or finally deciding to learn how to ride a bicycle.

The real-world reasons of the departures of the actors playing Doctor Who companions are much more grounded in the nitty gritty realities of contract negotiations, career aspirations, and changes in management.

Looking back over the companion exits of the modern era of Doctor Who, from 2005 to 2025 reveals a number of interesting things. In all three eras, from RTD1 to Chris Chibnall, a companion exit seems far more guided by story than it ever was in the classic era.

In RTD's first era, companions like Martha and Donna would be given specific character arcs that spread across one season. In the Moffat era, actors like Karen Gillan and Jenna Coleman had some input into their departures from the roles. In the Chris Chibnall era, the departure of one actor organically led to another companion leaving with them.

In the RTD2 era, however, the story reasons are still important, but much more difficult industry realities also play a role in showing the companions the TARDIS doors. So let's see how these companion exits have changed over the past 20 years of Doctor Who.

Billie Piper helped make Doctor Who an overnight sensation way back in 2005, but it was that popularity that played a small part in her decision to leave. Reflecting on Doctor Who in an appearance on Desert Island Discs back in 2019, Piper said that:

"It made me really famous again in that sort of mainstream fame way that I find really uncomfortable."

This fame and the increased public profile was also potentially damaging to her burgeoning career as an actor. And so to avoid typecasting - and the harsh glare of the limelight that Doctor Who shines on a person - Piper decided to leave the show behind after two years to pursue other acting roles in other popular shows like Secret Diary of a Call Girl and, more recently, Wednesday. 

Of course, we know that when Billie left the role in 2006, she had already agreed to return for season 4. Then she came back in 2010 for David Tennant's final farewell, and again in 2013 for Day of the Doctor, then finally appeared as the 16th Doctor/Rose/Bad Wolf in the closing moments of The Reality War.