Jonathan Sims is a British creator recognized for his work in audio drama, games, and literature, with a particular focus on horror. He is the mastermind behind the highly successful horror anthology podcast, The Magnus Archives, where he served as head writer, presenter, and voice actor. This project, initially conceived as simple spooky stories, evolved into a narrative with a complex meta-plot, eventually reaching over 100 million downloads. Sims also developed a sequel podcast, The Magnus Protocol, which achieved record-breaking crowdfunding success. Beyond audio, his creative endeavors include voice acting in video games like Slay the Princess and contributing to tabletop role-playing games through his company, MacGuffin & Company, which publishes system-neutral micro-settings. His writing career also encompasses two published horror novels, Thirteen Storeys and Family Business, with a third, The Burn Line, forthcoming. His work often delves into societal anxieties and fears, drawing inspiration from classic ghost stories.

Jonathan Sims is best known for creating and starring in the horror audio-drama podcast, The Magnus Archives. Launched in 2016, the show features Sims as a fictionalized version of himself, the Head Archivist of the Magnus Institute, who reads aloud submitted accounts of unsettling and unusual occurrences. While initially planned as an anthology of standalone spooky tales, the podcast developed a complex overarching narrative. The fictional persona of Jonathan Sims eventually diverged significantly from the real-life creator. The series achieved immense popularity, surpassing 100 million downloads on Spotify. Building on this success, Sims co-created The Magnus Protocol, a "side-quel" to The Magnus Archives, which garnered significant attention through a highly successful crowdfunding campaign, raising over £700,000. The show, co-written with Alexander J Newall, continues to explore the universe established in the original podcast.

Sims has established himself as a novelist, publishing two horror novels with Gollancz Ltd. His debut, Thirteen Storeys (2020), reimagines the haunted house concept within a London apartment building, exploring themes of class disparity between residents of luxurious front apartments and those in cheaper rear flats. His second novel, Family Business (2022), delves into the horror of grief and societal memory, following a character who takes a job with a specialist post-death cleaning service where the details of deceased clients become mysteriously elusive. Sims has a contract for two more novels, with the third, The Burn Line, anticipated in mid-2026. This upcoming work is described as a "breakup letter to London" and is set during a heatwave, focusing on residents trapped on the London Underground. His writing often draws inspiration from classic ghost stories, particularly M. R. James, and is noted for its ability to connect with deep-seated human fears and reflect societal issues.

Beyond his writing, Jonathan Sims is also active as a voice actor and games designer. He was a founding member of the musical cabaret group The Mechanisms, where he served as lead singer under the name Jonny D'Ville and co-wrote lyrics, performing steampunk, western, and cyberpunk interpretations of classic stories. More recently, Sims lent his voice talents to the acclaimed indie game Slay the Princess, portraying The Voice of the Narrator and The Voices in Your Head, a performance that received widespread praise for its vocal range and distinct character portrayals. He has also undertaken other voice acting roles, including Dr. John Seward in Re:Dracula and Alf in The Silt Verses. Additionally, Sims narrates classic ghost and horror stories on his personal online platforms and has contributed writing to the fitness app Zombies, Run!, the historical fiction podcast Outliers, and various short story collections.