The introduction serves three main purposes. First, I present the topic of the book and its main goal: to identify the Greek tragedies that ancient actors continued to stage from the fourth century BC to the third century AD. In addition to surveying the relevant scholarly literature, I also introduce the terminology used in the book. Second, I describe the four types of ancient sources that allow us to reconstruct the repertoire of ancient actors: inscriptions, literary records, tragedy-related vases and Roman tragedies. I discuss each category of records separately, presenting previous studies and addressing their contribution to my own work. Third, I summarise the four chapters making up the book and I describe how I have arranged the two Appendices collecting ancient sources, one related to identifiable Greek tragedies (Appendix I) and the other to their unidentifiable counterparts (Appendix II).