In this article, we introduce the Special Section on Extreme Speech and Global Digital Cultures by developing the concept of “extreme speech.” In addressing the growing cultures of online vitriol and extremism, this concept advances a critical ethnographic sensibility to situated online speech cultures and a comparative global conversation that moves beyond the legal-normative debates that have been dominant in North America and Europe. We demonstrate this intervention by highlighting three interlinked arguments: Extreme speech inhabits a spectrum of practices rather than a binary opposition between acceptable and unacceptable speech; the sociotechnological aspects of new media embody a context in itself; and the violence of extreme speech acts is productive of identity in historically specific ways. This approach entails a methodological move that takes account of the meanings online users attach to vitriol as historical actors. It thus allows for critical frameworks to emerge from emic terms of action rather than moral concepts superimposed from the outside. Ethnographic explorations of extreme speech, we suggest, open up a new avenue to critique the contemporary global conjuncture of exclusionary politics.