Doctor Who: Every Modern Companion's DEFINITIVE Episode

Recently, I selected my picks for each NuWho Doctor's quintessential episode. This time, we'll be looking at NuWho's companions. A companion's quintessential story isn't necessarily their best episode, nor is it their most emotional, or this list would be full of companion departure episodes.

For the purposes of this list, I'm qualifying 'quintessentialness' using a few factors. Firstly, does the episode capture what defines this companion - their core traits, their strengths and flaws? Secondly, does the companion drive the plot (there are plenty of episodes where they're front and centre, but we're looking for stories about them, not just stories where things happen to them)? Lastly, does this story work if you swap out the companion for someone else, or is it custom-built for that character?

I am including only televised companions from the 2005-2025 era of the show, and am keeping each companion to a single defining story. I'll be focusing on 'primary' companions here, but I've slotted in a bonus quickfire round for secondary companions who don't have quite enough spotlight to have a quintessential episode.

Before we get into the main list, and just so no-one is left out, here are my picks for some of the less-established companions of the modern run: 

Mickey – Rise of the Cybermen / Age of Steel 

The story where Mickey steps out of Ten and Rose's shadow and finally becomes his own man. He meets and loses the alternate version of himself, gets to save the day, and finds a new family in Jake and Parallel Pete. He also finds the purpose he's been lacking and makes the decision to stay in the parallel world, which is the perfect bookend to two series' of development.

Nardole – Extremis 

This story forces Nardole to take the lead, with the Doctor still struggling to manage his blindness, with Nardie ultimately taking on the Doctor role in his and Bill's plotline. He's got some great comic moments, solid moments of deduction, and a little more humanity than he'd had up to this point. Not to mention the reveal that he's secretly a badass.

Graham – It Takes You Away 

This is Graham’s episode. He finally gets to confront his grief with grace in a healthy and interesting way, and is able to take some major steps to deepen his bond with Ryan. Bradley Walsh gets to flex his acting muscles properly to genuinely touching results. Also has a talking frog. 

Ryan – Resolution

One of very few stories focused on Ryan and one of the only outings where he acts with his own agency and makes decisions. Deals with Ryan's troubled relationship with his father that was hinted throughout series 11. A good showcase for how Ryan could have been more compelling if he was actually given stuff to do. 

Dan - War of the Sontarans 

Dan doesn't really have a defining episode and feels like he's mostly there for the lols. But War of the Sontarans is probably his peak simply because Wok-gate is iconic in the dumbest way possible and spawned some quality memes. There are worse legacies to have!