This essay addresses what we can call epistemology’s Prime Evils. These are the three demons epistemologists have conjured that are the most troublesome and the most difficult to dispel: Descartes’ classic demon; Lehrer and Cohen’s New Evil Demon; and Schaffer’s Debasing Demon. These demons threaten the epistemic statuses of our beliefs—in particular, the statuses of knowledge and justification—and they present challenges for our theories of these epistemic statuses. This paper explains the key features of these three central demons, highlights their family resemblances and differences, and attempts to show that a certain kind of internalist view of justification provides the resources to handle these demons well.