Transgender

Among humans, a transgender person was someone whose gender did not align with that which they were assigned at birth. The term was used as an adjective, often shortened to simply "trans".

Non-binary people were also or could also be trans. Calypso Jonze self-identified as trans and non-binary, (AUDIO: The Lovecraft Invasion) and used they/them pronouns. (AUDIO: "Flight of the Blackstar")

Mickey Smith had a trans friend called Sally Salter, who was part of his Bad Wolf band. (PROSE: Rose) Jack Harkness once had a transgender co-worker, Vanessa, who changed her name, something that perplexed Jack. (TV: Greeks Bearing Gifts)

Eleanor Blake, an accomplished mathematician who met the Seventh Doctor and entered a brief romantic relationship with Chris Cwej, was a trans woman who lived through the 1940s. She went on to travel with Alpha Wheeler throughout space to escape the discrimination she faced on Earth. (AUDIO: The Jabari Countdown)

Tania Bell was a trans woman who worked for Torchwood Three. She was a resident of 107 Baker Street. She later became a companion of the Eighth Doctor, as well as Liv Chenka's romantic partner, on 2020 Earth. (AUDIO: Must-See TV, Wild Animals, Dead Time) She was accustomed to other people "minding" that she was trans, (AUDIO: Wild Animals) but understood that the identity one forged for oneself was truer than the "shot in the dark" that was birth assignment. She chose her name to affirm who she really was. (AUDIO: The Long Way Round)

Because gender was commonly assigned at birth, (TV: Day of the Moon, Father's Day, AUDIO: The Long Way Round) trans people like Sally Salter (PROSE: Rose) and Eleanor Blake came to realise that they had always been a different gender to that which they had been told. Despite others' non-acceptance, Eleanor was fully aware that she had "always been Eleanor". (AUDIO: The Jabari Countdown) In the mid-2000s, Sally had to cut ties with her family in order to begin living life as herself. She found affirmation with her friends and bandmates, together known as Bad Wolf, and a safe space in which to sleep at Mickey's one-bedroom flat. (PROSE: Rose)

"Earth takes its time on too many things, and [trans rights] is one of them. Not in this century, I'm afraid. Though the next one is... a little better."

- Seventh Doctor

Though, according to the Seventh Doctor, circumstances would improve "a little" by the 21st century for trans people, Eleanor had to hide her identity in order to survive in the 1940s. In fact, Eleanor faced violence and discrimination on account of her gender. She was surprised to find Chris Cwej so accepting, noting how he "didn't even blink", but held little hope for changes to come within her lifetime.

Coming as he did from the 30th century, Chris did not understand the fuss about assigned genders. As he explained to Eleanor, on first finding out she was a trans woman, "it seems a bit stupid to care about little stuff like that", considering the breadth of the universe, and all the dangers and variety to be found therein. (AUDIO: The Jabari Countdown)

"A few years" prior to her discover in 3909 that she was actually an android who'd been subjected to illegal fleshing, Emily suspected her dysmorphia and spiritual malaise about her existence (actually an effect of the fleshing process) might have meant she was trans. She used a holosimulator to test out the feeling of living as other genders, but they did not nothing to alleviate the malaise, and she dismissed the theory, annoyed that "her feelings couldn't have the decency to be the result of something normal". (PROSE: Cybergeddon)

Cassandra O'Brien.Δ17 also once claimed to Rose Tyler that she had once been "a little boy" on Earth, although she was notoriously prone to misusing words and knowledge from her early Earthly life. (TV: The End of the World)

Conall Lethbridge-Stewart knew some people who were trans and had told his younger sister, Lucy Wilson. (PROSE: Sweet Revenge)

When Cleo Proctor was kicked out of her house by her mother in 2012 when beginning her transition, Jordan Proctor took her in. (AUDIO: SOS)

Miles Werbiansky, by March 2011, had transistioned. (PROSE: A Worthy Successor)

Writers
In 2011, trans woman Lilah Sturges wrote the IDW comic story A Fairytale Life. Sturges was credited by her birth name for the story as she "didn't consciously know [she was transgender] until 2012".

Jay Harley was the assistant director for Series 6 and writer of Zero Hour and The Good Master for Big Finish in 2017. They later came out as non-binary.

In 2018, Juno Dawson, another trans woman, wrote the BBC New Series Adventures novel, The Good Doctor.

Also during this time, Niki Haringsma wrote two Faction Paradox short stories: A Scene and What Keeps Their Lines Alive.

Later in 2018, "tubular transdudette" Doris V Sutherland wrote PROSE: The Bunny's Curse. She would go on to write another Bernice Summerfield story, AUDIO: Clear History, in 2019.

In 2020, Amy Veeres wrote the Ninth Doctor Short Trips audio story Her Own Bootstraps.

That same year, Grant Morrison came out as non-binary. Although no longer associated with the DWU by that point, they had previously written three comic stories for Doctor Who Magazine, which were reprinted in Grant Morrison's Doctor Who.

Stacey Smith? wrote the short story The Church of Saint Sebastian in 2005, prior to coming out as a trans woman in 2021.

Actors
Lor Wilson, who portrayed Lucy Cartwright and Daughter of Mine in Human Nature / The Family of Blood, later came out as non-binary. They reprised their role in the 2020 webcast The Shadow in the Mirror.

In 2015, Bethany Black became the first openly transgender person to be cast in an episode of Doctor Who, series 9's Sleep No More. She played the role of 474.

Adèle Anderson, a trans woman, had a guest role in the 2017 Big Finish audio story The Carrionite Curse. She later played a series of clones named Dreyda in the Jenny: The Doctor's Daughter audio story Zero Space, and held a recurring role as the Sixth Tamasan starting with the Eighth Doctor: Time War: Volume Three box set.

In 2020, Rebecca Root began her role in Stranded as Eighth Doctor companion Tania Bell, who was the first trans companion in the Doctor Who universe. She also portrayed cis characters in earlier Big Finish stories.

That same year, non-binary actor Robyn Holdaway had a role in AUDIO: The Lovecraft Invasion. They played Calypso Jonze, a trans, non-binary bounty hunter from the 51st century. This became a recurring role in 2021, with The End of the Beginning.

Other
In 2018, Vera Wylde (host of Doctor Who YouTube channel Council of Geeks) came out as non-binary. They have since revealed that they relate to the Twelfth Doctor due to his character arc of accepting who he is and not wanting to change.