This book covers key topics regarding the research and creation of personas across cultures for human-computer interaction (HCI). Through empirical cases studies, it examines a breadth of approaches, challenges and reflections on personas deployed in different locales over time. Personas have been artefacts of enquiry and praxis since Alan Cooper brought them to mainstream technology design. Yet, their study and emergence across cultures have been little explored –least of all synthesised in a monograph, this book fills that gap. It consolidates the body of work on persona studies conducted in a variety of locations in India, Brazil, Kyrgyzstan, Namibia, Vietnam, Chile, Mozambique, Malaysia and South Africa, drawing upon two somewhat competing, if complementary methodologies: User-Centred Design and Participatory Design. Rather than prescribing tools, techniques, methods or methodologies, it illustrates the historical versatility and epistemological plasticity of personas in the design of technologies shaped by dominant, situated, inclusive or culturally nuanced representations of people. It draws from the author's extensive knowledge of case studies as well as from his own work to provide examples, reflections and audiovisual illustrations of relevant concepts and issues.  Personas Across Cultures: Representing the Next Billion Users is designed for early and seasoned career researchers in HCI who might approach the design of personas across cultures for the first time, and scholars and practitioners in related fields such as interaction design, usability, user experience and co-design.