That “grim jester with a twisted brain,” Batman supervillain the Joker reflects shifting social constructions of mental difference in the US across eight decades. The article reads Batman serial comics, graphic novels, and film against four key moments in Mad History: eugenics, psychiatric survivor activism in the 1960s and 1970s, the trauma discourses of 1980s popular culture, and the criminalization of mental difference in the twenty-first century. Out of this complex conversation four models of madness are derived: toxic reproduction, liberation, mad genius, and the conflation of madness with violent crime. These models work intersectionally: Joker’s madness, queerness, and exceptionally white masculinity engender each other. Because of his distinctive qualities as a visual icon, he makes Mad History more visible, too.