This chapter argues that Hamlet’s status as the preeminent early modern instantiation of modern subjectivity, which dates back to the romantic era, is predicated upon the downgrading of Senecan tragedy’s status and upon misunderstanding the nature of Shakespeare’s relationship with the Senecan tradition. Senecan tragedy as a tradition offers resources for thinking about self-assertion and its limits, and these underpin questions about agency, choice and pre-scriptedness that have been foundational for the tradition that sees Hamlet as a “tragedy of thought.” Hamlet’s post-Freudian association with Oedipus, meanwhile, though traditionally associated with Sophocles, is better understood as part of what we might call a Senecan Oedipus complex. In Senecan tragedy (including Seneca’s Oedipus) the figure of the mother is one symbolic representation of the limits of human autonomy, but the symbolic meaning of the figure of the mother is not limited to a domesticated narrative of infantile development. Critics have asked why Hamlet, of all plays, should have become the key proof text for modern theories of subjectivity and psychology; this chapter suggests that the nature of the play’s engagement with Seneca may be a major reason.