Sara B. Elfgren is an award-winning Swedish writer, screenwriter and playwright. She made her debut with the YA novel The Circle (2011), which she co-wrote with Mats Strandberg. The Circle was the first part in the Engelsfors trilogy, and it has been translated into twenty-five languages. Since her debut, Elfgren has written critically acclaimed novels, children's books, graphic novels, audio dramas, screenplays and TV scripts. Her plays have been performed on some of Sweden's most prestgious stages. She has even written a VR Game, the award-winning, heart-warming and heartbreaking Ghost Giant (2019). Her graphic novels Vei 1 and 2, which she co-created with illustrator Karl Johnsson, made Mike Carey exclaim: "Wonderful stuff!" and Lev Grossman said: "You cannot miss it." When The Circle was made into a movie Elfgren co-wrote the screenplay with the film's director Levan Akin (And Then We Danced, AMC's Interview with the Vampire). In 2022 the TV series Dough, for which Elfgren was one of the head writers, was awarded the most prestigious Swedish TV award Kristallen for Best Drama Series.

She was born in Stockholm and still lives there. She has a degree in Film Studies. She enjoys reading, watching old movies, listening to music, playing video games and going for long walks. She is currently working on an opera libretto.

She has been nominated for or won a number of literary awards:
2021 – Winner of the Urhunden Award
2020 – VEI, Book 1 – Silver medal in the IBPA Benjamin Franklin Award
2018 – In Dreams – Swedish Audio Award, Best YA-of-the-year
2018 – In Dreams – nominated to the Nordic Council Children and Young People’s Literary Prize
2019 – The White Reindeer Award
2012 – Fire – Book Jury Prize