Laetittia Barbier traces the macabre origins of the wax museum all the way to the foot of the 18th century guillotine:

Behind the scaffolds, a 32-year-old woman undertook the gruesome labor of casting in wax the severed heads of the enemies of the [French] Revolution. The effigies were then paraded on picks in the streets as symbolic sacraments of the people’s victory. The dilligent wax manufacturer’s name was Marie Grosholz, a name she promptly changed after her wedding to become Madame Tussaud.

(Photo: “Madame Tussaud making wax likenesses of guillotine victims in Paris” at the Royal London Wax Museum by Herb Neufeld)