This edited volume engages with Barbie (Greta Gerwig, 2023) and Oppenheimer (Christopher Nolan, 2023) through the lens of the “Barbenheimer” fad, an online and in-person phenomenon that celebrated the counterprogramming of these two divergent films. Through a variety of approaches and perspectives, Barbenheimer Syndrome reveals why these movies struck such a cultural nerve.Before Barbie and Oppenheimer even hit screens on July 21st, 2023, “Barbenheimer” was already a cultural sensation. A term coined by critics and co-opted by fans, the “Barbenheimer” portmanteau encapsulated the absurd juxtaposition between a pink-soaked ode to the popular children’s doll and a dark biopic of the inventor of the atom bomb playing simultaneously at the multiplex. The two films smashed expectations at the box office. Memes of pink mushroom clouds, think-pieces interpreting one or both films, and red-carpet photographs of Barbie and Oppenheimer’s casts flooded social media well past the films’ July release. “Barbenheimer” was having a moment.This edited volume revisits that moment to interrogate the logics behind the cultural spectacle created by this simultaneous release. By framing “Barbenheimer” as a syndrome, contributors consider not only the elements that constituted the phenomenon on a global scale, but also the ways in which this phenomenon was symptomatic of larger cultural forces and social changes occurring at the time of release. The editors of this volume have assembled a comprehensive roster of contributors who interpret Barbie, Oppenheimer, and “Barbenheimer” through diverse disciplinary approaches and in different cultural contexts to explore the universal and specific iterations of the global “Barbenheimer syndrome.”