Bill Potts

Bill Potts works the chip counter in a university canteen and sneaks into a professor's lectures because his ideas are the only thing in her week that feels like it matters. She's curious, funny, unfiltered, and asks the questions anyone would actually ask when confronted with something impossible — which is exactly why the Doctor takes notice of her.

The show finally lets a companion react like a real person: Bill narrates the absurdity out loud, doubts, panics, laughs at the wrong moments. Pearl Mackie plays that openness without ever making her seem slow on the uptake — she's delighted and skeptical in the same breath, and her ordinary, working life grounds the show's wilder swings.