The social sciences and institutional theory have seen the proliferation of the term actor and the profusion of its meanings. Despite the importance and ubiquity of actor in institutional theory, the term is largely taken-for-granted, which has stunted the development of institutional theories of actors. The authors aspire to spur theorization of actor in institutional theory in the hope of carving out institutional theories of actor in the collective research agenda. The authors first contextualize their interest in actor in institutional theory and discuss the intellectual context within which the authors put this agenda forward. The authors briefly sketch out the main themes that would provide fruitful areas of inquiry in this new agenda and bring together a variety of strands in institutional theory with a clear focus on the relationship between institutions and actors. The authors conclude by discussing the contributions included in the volume.