Requirements engineering (RE), an early phase in software development, is the process of discovery, analysis, modelling and specification of user and business requirements for information systems. The lack of creativity theories and models within RE has been gaining increasing recognition within the RE community. This paper synthesises concepts from creativity research and RE creativity research to build a theoretical foundation for the study of creativity in RE. We argue that creativity in RE goes beyond technical aspects and involves different levels, loci, and inter-related elements including product, process, domain, people and socio-organisational context. Different facets of creativity need to be integrated within RE approaches and methods to effectively foster and support creativity in this field.