Tzim-Sha

Tzim-Sha, (PROSE: The Secret in Vault 13) also spelt T'zim-Sha, (WC: Case File One) was a Stenza warrior who sought to become the leader of his people. He was nicknamed "Tim Shaw" by the Thirteenth Doctor, due to her mishearing his true name. (TV: The Woman Who Fell to Earth) He was continually referred to as Tim Shaw, such as when Yaz spoke about him on Desolation. (TV: The Ghost Monument)

He used a swarm of gathering coils in order to locate a trophy to take back to his planet, despite this being against his species' rules so he could win the leadership of his people.

He came ahead in his pod, waiting inside for the coils to find his target before breaking out and killing Rahul, taking one of his teeth as a prize. He then began searching for the coils in order to learn where and who his target was. While searching for the coils, he encountered Dean, who threw salad at him, mocking his appearance. Angered, Tzim-Sha killed him and took one of his teeth as well.

Upon finding the coils, he was confronted by the Doctor, along with Ryan, Graham, Grace and Yasmin who ordered he not hunt on Earth and flee back to his people. However, Tzim-Sha refused, threatening to kill the Doctor if she tried to stop him. He absorbed the data and then used a short-range teleport to reach his target, Karl Wright, at a construction site.

There, he killed the security guard and proceeded to climb up Karl's crane to reach him. However, the Doctor arrived with assistance and proceeded to convince Karl to leave his crane and climb towards her so he could jump to safety. However, Tzim-Sha caught up to them, grabbing Karl to take back with him. Not giving in, the Doctor leapt across, stating he couldn't leave as she had stolen the recall device from his pod that would allow him to return home and threatened to destroy it. Calling her bluff, Tzim-Sha detonated the DNA bombs his coil implanted in the Doctor and the others.

However the detonation affected him instead as the Doctor has transferred the bombs into the coil's data, meaning Tzim-Sha had downloaded them. With no choice, Tzim-Sha let Karl go and took the teleport to flee back to his planet, but not before Karl kicked him off the railings. (TV: The Woman Who Fell to Earth)

As the recall device had been corrupted, the teleport took him instead to Ranskoor Av Kolos where he wouldn't be able to leave without dying. However Ux Andinio mistook him for their creator and thus helped him regain his health and strength and assisted with his plans for civilisation wide conquest. Tzim-Sha spent over three thousand years trapped on the planet, planning his revenge upon the Doctor and her companions.

After another attempt to defeat the Doctor and her companions, he fell to Graham O'Brien and Ryan Sinclair. Though they had the chance to kill him, the two chose not to and instead locked Tzim-Sha in a stasis pod of his own making, essentially sentencing him to life imprisonment. The two ordered him to think of Grace O'Brien as they left. The building was then sealed to prevent anyone from ever getting to Tzim-Sha and freeing him. (TV: The Battle of Ranskoor Av Kolos)

Behind the scenes
This character's name was given several different ways by official sources. He was listed by his Doctor-given nickname "Tim Shaw" in the credits for TV: The Woman Who Fell to Earth and in some BBC marketing elements. In at least BBC America, ABC iView and iPlayer closed captioning, the non-English variant is rendered as Tzim-Sha.

A Case File video about the Stenza also calls the character "Tim Shaw" but renders the real name with an apostrophe: T'zim-Sha. Because the font used in this Case File is all uppercase, however, even it doesn't settle whether the real name should be T'zim-Sha or T'Zim-Sha.

Finally, the children's novel The Secret in Vault 13 confirmed Tzim-Sha as the spelling, which would later be used on television via the credits for TV: The Battle of Ranskoor Av Kolos.