We introduce “parasitic publics” as a necessary, generative addition to scholarship on publics and counterpublics. Parasitic publics are reactionary discursive spaces formed residually and institutionalized affectively through the invention, circulation, and uptake of demagogic rhetorics. They feed off of oppressive conditions in the public sphere by (1) articulating with dominant discourses to exploit dominant publics’ centripetal force and (2) safeguarding the assemblage of dominant publics against counterdiscursive challenge. To illustrate and elaborate on this concept, we use articulation theory to analyze a highly organized white nationalist collective that swarms digital forums and comment sections. Founded by a former Republican congressional aid and Ronald Reagan appointee, this collective maintains training podcasts on their politics and debate strategies, two different databases of copy-and-paste rhetorics, two rhetorical style guides, and a subforum through which they direct each other to swarm digital spaces. We conclude with implications for future research on contemporary public spheres.