This article aims to paint a portrait of a massacrer who was both known and unknown during the Saint Bartholomew’s Day massacre: Thomas Croizier, perhaps one of the worst executioners of the Parisian matins. This paper will first consider the posterity of this man, widely cited by historians as the “gold shooter,” a strange profession that shields our knowledge of the man behind the trade. It will then question the why and the how of the violence committed by Croizier. If it is always delicate to reconstitute ideological motivations or religious beliefs a posteriori, this paper will try to determine the intellectual or imaginary context in which Croizier moved. The conditions that allowed Croizier to become a murderer will be analyzed – vicinal, professional, family, and friendly settings. One is not born a killer, one becomes one. Finally, because the executioners were never prosecuted, we will look at what happened to Thomas Croizier after the Saint Bartholomew’s Day massacre.