The Marlovian stage-Jew exhibits a magnificent range of mental disturbances, including a penchant for extreme violence, a perverse interest in toxic substances, and a predisposition for obsessive egotism. Rather than an inventive presentation of the character’s wickedness, this variegated display of depravity reflects the psychological profile of the Jew according to the shared vision of playwright and playgoer in early modern England. This essay argues that Christopher Marlowe’s Barabas manifests a madness that was recognizable to spectators as a Jewish infirmity and an extension of the broader corporeal denigration of and associated disgust for Jewish men. By tracing the roots of that malignant representation back to ecclesiastical illustrations of the medieval period and also drawing connections to contemporary medical texts that linked impure blood and poor hygiene to mental dysfunction, the essay articulates the medical logic that underpins Barabas’s madness in The Jew of Malta. Ultimately, the essay shows the comprehensive nature of early modern English fantasies about Jewish alterity and uncovers the multidimensional layers of biological difference, both somatic and psychological, that were intrinsic to the theater’s constructions of Jewishness.