From Wikipedia:
La Reine Margot (English:Queen Margot) is a historical novel written in 1845 by Alexandre Dumas, père.
Although La Reine Margot is based on real characters and events, certain aspects of the novel may be inconsistent with the historical record; historians have attributed that to artistic licence and the fact that Dumas might have been influenced by propaganda against certain historical figures, notably Catherine. Written in French, it was almost immediately translated into English, first anonymously and soon afterward by David Bogue as Marguerite de Valois: An Historical Romance.