Doctor Who: 10 Unresolved Storylines & Mysteries That Need To Be Explored

We all have a dark side to us, someone that we call our"evil twin" or provide a comical nickname for. We're all well-versed on the Doctor's: the Valeyard, an amalgamation of the darker sides of their nature, who manifests somewhere between the Doctor's twelfth and final incarnation.

Of course, The Time of the Doctor and ongoing Timeless Child arc has retconned that particular theory. Still, time can be rewritten.

Nevertheless, we've seen the Dark Doctor in various forms, most notably the Time Lord Victorious from The Waters of Mars and recent cross-media epic of the same name; and a psychic version called the Dream Lord (Toby Jones) in series 5's Amy's Choice.

Season 23's The Trial of a Time Lord marked the Valeyard's first and last on-screen appearances, played with menacing relish by Michael Jayston. It was only fitting, therefore, that he leant his dulcet tones to Big Finish's superb Sixth Doctor regeneration storyline.

Yet, the spectre of the Valeyard has been foreshadowed during the NuWho era - by the Great Intelligence in The Name of the Doctor, and mentioned as part of many major spoilers for a shellshocked First Doctor in Twice Upon a Time. So he's lurking in there somewhere.

For a character steeped in Who lore, the Valeyard needs a worthwhile story arc if they ever return to TV. Again, let the dream casting commence.

Richard Armitage, who portrayed a Big Finish version of Rassilon, comes to mind. The charismatic actor has played some pretty unsavoury and downright evil characters, was a fan of the show growing up, and has got the beguiling baritone voice to boot.