When it comes to brains, The Doctor is arguably the smartest character in Doctor Who. Their immortal brain and naturally inclined intellect has resulted in a character that is more brilliant than most fictional heroes. The Doctor’s superpower is their brain.
But, even when they think they’re the smartest ones in the room, sometimes The Doctor’s companions can give them a run for their money. Over the long history of the series, companions of the series have proven to be some of the more brilliant characters on the show.
Ian Chesterton
A companion to the First Doctor, Ian Chesterton was a school teacher at Coal Hill School, the institution where the Doctor’s granddaughter Susan attended. Along with his colleague Barbara, he traveled the universe alongside The Doctor.
As a science teacher, Ian was already rather brilliant, holding a strong sense of the fabric of reality. But, more than that he brought with him emotional intelligence. The First Doctor Struggled with his empathy, especially towards humans. Ian was one of the first people to inspire this trait to improve in The Doctor.
Barbara Wright
Traveling alongside Ian, Susan, and the First Doctor, Barbara Wright was also a teacher at Coal Hill School. This alone made her and Ian a step above many of The Doctor’s Companions, being individuals with high intelligence and specialized interests.
Barbara herself was a History teacher, obsessed with cultures and societies of the past. Her knowledge of the Ancient Romans and Aztecs proved useful when confronted by those exact cultures in their own time. Barbara was equally, if not more so crucial to The Doctor’s budding love of humankind.
Sarah Jane Smith
Sara Jane Smith is one of the most beloved companions of all time. Her tenure in the classic series is one of the most fondly remembered, for both her performance and Tom Baker’s. She eventually returned to the series through a few short stints alongside David Tennant as well as through her own spinoff.
Paired off with K-9 and her son, Sarah Jane’s brains were really on display in latter appearances. Her knack for technology was useful when confronted by alien species and caring for K-9. But her investigative abilities were incredibly useful as well.
Rory Williams
Rory Williams had quite the life (lives?). Even when fans first met him, Rory was a nurse in training, learning all the necessary skills as a health practitioner. Though these skills didn’t always come up, when they did they were incredibly helpful.
Throw in the fact that Rory lived multiple lifetimes as the Centurian and what you get is an individual with perspective, unlike many other companions. Living through almost all of western civilization, Rory saw the huge leaps and advancements of society in real-time.
Clara Oswald
Clara Oswald alone was a bit of a ditz in her early days. She couldn’t even figure out how to use the wifi in her first outing in the Bells of St. John. But, as the writing improved and her role became more substantial, so did her brilliance.
Clara soon became nearly as smart and cunning as the Doctor. After seeing all the lives that the Timelord had and would live, Clara gained an understanding, unlike any other companion. Soon she would have the mental intelligence and emotional security to go up against the likes of Cybermen, Daleks, and Missy herself.
Liz Shaw
Not as many modern fans might remember Liz Shaw, but she remains one of the smartest in the history of the series. A Cambridge educated scientist, Liz accompanied the Third Doctor through his adventures on Earth.
Liz put her skills to the test at the United Nations Intelligence Taskforce, a.k.a U.N.I.T., as a contracted scientist. It was here when she first ran into the Third Doctor while battling the feared Autons. Educated at one of the best schools the U.K. and the world has to offer, she was second to none in terms of intelligence resources.
Martha Jones
While Liz was a brilliant scientist, she was still limited by the resources of her time. Martha Jones is very similar in comparison but had a bit more experience and the added benefit of living in the 21st century.
Martha trained to become a Doctor, quite the step above Rory’s training, and worked for U.N.I.T. and Torchwood. Not to mention, she had to confront the evil of the Master head-on, traveling the globe alone for a year. She remains one of the smartest and least celebrated companions of the whole series.
Captain Jack Harkness
Jack Harkness has had quite the history as a former time-agent turned rogue scoundrel turned Torchwood head. His experience as a companion to the Timelord led him on a journey across all of space and time, and his nearly immaculate face remains the proof.
This slowly aging immortal rogue isn’t just a pretty face. His understanding of alien species, cultures, and time phenomena is unlike most normal companions. He has lived a life nearly as long as The Doctor once becoming the Face of Boe.
River Song
River Song is very similar to Captain Jack. She is a brilliant time-traveling former companion to The Doctor who is also quite the flirt around most she meets. But, unlike Jack, River is an academic first and foremost.
River trained and studied to become the lead archaeologist in the history of the universe. While she might be called a cheater for her time-traveling methods, her experiences traveling alongside The Doctor combined with her natural intelligence leave her brains fairly unchallenged.
Romana
Romana is one of the only companions that might have been just as if not more brilliant than The Doctor. A fellow Gallifreyan, this Timelady saw two regenerations during her time alongside The Doctor, each with their own brand of wit.
No matter the version of Romana, the fact that she is an immortal Timelady like The Doctor means that her understanding of the universe is far beyond that of any other companion. A Gallifreyan herself, her and The Doctor were a nearly unstoppable team.
