With contributions from a distinguished group of world-builders, including academics, writers, and designers, this anthology of essays describes the process and discusses the nature of subcreation and the construction of worlds. From Oz to MUD, Walden to Rockall, all the worlds featured in this volume share one thing in common: they began in someone's imagination, grew from there, and became worlds built with the assistance of multiple authors and a variety of different ideas and media, including designs, imagery, sound, music, stories, and more. The book examines this development, with examples and discussions pertaining to the process and the final product of the building of imaginary worlds, including some transmedial worlds. World-Builders on World-Building is a fascinating deep dive into the practical problems of world-building as well as its theoretical aspects. It is ideal for students, scholars, and even practitioners interested in media studies, game studies, subcreation studies, franchise studies, transmedia studies, and pop culture.