This book surveys all the instances of revenge in the eight tragedies written by the Roman philosopher Lucius Annaeus Seneca. It focuses especially on the following six plays: Agamemnon, Phaedra, Medea, Troades, Hercules furens, and Thyestes. The most significant result of this survey is that most of the characters who desire revenge and enact it, or try to do so, are female. On this basis, the book argues that it is primarily through the revenge of female characters that Seneca interrogates the boundary between proportionate and excessive revenge and explores the problems inherent in like-for-like violence. It then goes on to highlight, and analyse, the connections between the parameters of revenge as depicted in the tragedies and the role of revenge in Seneca's Stoic philosophical treatise On Anger, emphasizing the extent to which revenge is central in both parts of the Senecan corpus, the tragedies and the philosophy. Finally, it presents an innovative argument in favour of the unity of the two parts of the corpus. This argument consists in showing how, both in the tragedies and in On Anger, Seneca incorporates elements of Stoic readings of Greek tragedy, and Euripides' Medea in particular, a tragedy which by Seneca's time already had a long reception history in Greco-Roman literature and philosophy. Medea's revenge is therefore a special case which proves essential not only for assessing properly the dynamics of revenge in Seneca's tragedies, but also for gaining a holistic understanding of Senecan revenge.