This chapter discusses both the dramatic and the literary canons of Greek tragedy. First, I review the plays that entered the repertoire of ancient actors by focusing on the elements that they share. These include specific features, scenes and motifs, ranging from accessible Greek to large main roles, recognition and reunion scenes, mad heroes, the legends surrounding Dionysus and those related to Athens. Second, I discuss the scholarly activities that preserved most of the extant tragedies. My discussion spans from fourth-century Athens to the Byzantine period. Drawing from literary and papyrological sources, I identify the reasons underlying the literary selection of Greek tragedies: a narrow focus on the three canonical tragedians, generic definitions, considerations about specific authors and plays as well as pedagogical needs. Finally, I discuss the relationship between the two canons, arguing for their independence. They derive from two different kinds of selection, each driven by its own set of criteria.