For further understanding of spree killers, we explored fan communities of the same on Tumblr. We aimed to fit their expressed paraphilic desires with earlier typologies of aggressive/passive hybristophiles (women who fetishize killers) and a previously proposed typology of spree killers themselves. Tumblr fan site content (text and pictures) was investigated using a combination of visual and textual content analysis, latent class analysis, and hierarchical cluster analysis, using other celebrity fan sites as controls. The general trend was for hybristophiles to have surprising levels of self-knowledge with a small sub-set expressing worrying tendencies to fetishize the killings themselves over and above sexual desires towards the perpetrators. Although the division of hybristophiles into active and passive has been previously shown, we believe we are the first to link this to spree killers who are more or less explicitly advertising their behaviors to their fan base. Much attention has been directed to issues of so-called toxic masculinity and incels, but it is important to appreciate that they do not exist in a vacuum. This material contributes somewhat to understanding the toxic soil in which killers flourish.