This article investigates one of the most curious figures in the anti-Jesuit arsenal, the female Jesuit, or Jesuitess. In the middle decades of the nineteenth century, opponents of the Jesuits in a range of nations warned that the bedrock institutions of society were vulnerable to infiltration by this figure who in their mind combined Jesuit cunning with feminine charm. This made the female Jesuit, in words that were repeated in exposes of the Society, even more dangerous than the male Jesuit. Perhaps paradoxically, the female Jesuit tells us a great deal about the imagined nature of Jesuit masculinity. The existence of such a creature could seem plausible because Jesuitism itself appeared to be shrouded in an ambiguous masculinity. As an imagined space where gender confusion rather than clarity was thought to reign, the Society of Jesus naturally spawned a figure like the female Jesuit.