The one who was partially responsible for plotting the Saint Bartholomew’s Day Massacre was Catherine de Médicis. She's the mother of the French King, Charles IX. This happened because she feared Gaspard II de Coligny's, Huguenot leader, influence over his son. She approved the plot created by Roman Catholic house of Guise to assassinate Coligny, which resulted to the murder (done by Coligny himself) of François de Guise instead.
