The Creepiest Thing Ever: L'Inconnue de la Seine
In the early 20 century, a popular piece of art for the fashionable French home was "L'Inconnue de la Seine" (translation: "The Unknown Woman of the Seine"), a completely creepy death-mask of a young woman whose body had been pulled from the Seine River in Paris, sometime in the 1870s or 1880s.
As the (somewhat questionable) story goes, a pathologist at the morgue found the unknown woman's face enchanting, so he made a death mask—a plaster casting of her face. The resulting cast was widely reproduced and became both a popular objet d'art, as well as extremely influential to writers, artists, and indeed young girls who attempted to replicate her (dead) looks. (And you thought your friends were goth in high school.)
Having said all that, there are some questions as to the real origin of the mask (whether its source was indeed a dead woman or if it was a life mask from an unknown living woman who never spoke up), but let's just stick with the standard story and see how creepy it gets, shall we? As Wikipedia explains (emphasis added):
In the following years, numerous copies were produced. The copies quickly became a fashionable morbid fixture in Parisian Bohemian society. Albert Camus and others compared her enigmatic smile to that of the Mona Lisa, inviting numerous speculations as to what clues the eerily happy expression in her face could offer about her life, her death, and her place in society. The popularity of the figure is also of interest to the history of artistic media, relating to its widespread reproduction. The original cast had been photographed, and new casts were created back from the film negatives. These new casts displayed details that are usually lost in bodies taken from the water, but the apparent preservation of these details in the visage of the cast seemed to only reinforce its authenticity. Critic A. Alvarez wrote in his book on suicide, The Savage God: "I am told that a whole generation of German girls modeled their looks on her." According to Hans Hesse of the University of Sussex, Alvarez reports, "the Inconnue became the erotic ideal of the period, as Bardot was for the 1950s. He thinks that German actresses like Elisabeth Bergner modeled themselves on her. She was finally displaced as a paradigm by Greta Garbo."
But wait, it gets creepier: Have you taken a CPR class? Then perhaps you've locked lips with L'Inconnue; in 1958, the woman's face was used on the first CPR doll, dubbed Rescue Annie. Some have thus called hers "the most kissed face of all time," despite all these kisses occurring roughly 80 years after her death. No, not creepy in the slightest.
"L'Inconnue de la Seine" was a major inspiration for artists of all kinds. In "Influence and Authenticity of l'Inconnue de la Seine" by Anja Zeidler, it is revealed that L'Inconnue influenced artists including Albert Camus, Rainer Maria Rilke, and Anaïs Nin, among others.
You can read more about L'Inconnue de la Seine and the Rescue Annie story from Snopes.