Book excerpt: The Multiverse as Theory in Postmodern Speculative Fictional Narratives considers the concept of the multiverse beyond the immediacy of being merely an excuse or scenario for the development of stories, instead positioning the multiverse as a theoretical method in which speculative fiction narratives can explore diverse issues to bridge ideas across cultural, social, and philosophical analysis. Taking a cross-cultural approach, the book centres around the critical engagements that literary and media texts have with the representations of the multiverse, beyond considering this subject as a mere rhetorical flourish or a passing fad. A diverse and international team of authors engage with the multiverse from the point of view of “other worlds,” understanding it not as the appearance of another independent world, but as the collision of two or more different worlds into one of them. From this key finding, the multiverse encourages us to pay attention to the influence that fiction exerts on narratives and world-building, providing possible frameworks to rethink critical aspects of temporality, space, self, society, and culture in contemporary times. This pioneering work will interest students and scholars working in the areas of media and cultural studies, comparative literature, popular culture studies, speculative fiction, and transmedia studies.