He is mostly remembered today for his co-creation with Marcel Allain of the fictional arch-villain and master criminal Fantômas.

In 1909, already a published author, Souvestre co-wrote, with his friend and assistant Allain, their first novel, Le Rour.

Investigating Magistrate Germain Fuselier, later to become a recurring character in the Fantômas series, appears in this first novel.

In February 1911, Allain and Souvestre began the Fantômas book series at the request of Joseph-Arthème Fayard (fr), a publisher, who wanted to create a new monthly pulp magazine.

[2] Souvestre's former girlfriend, Henriette Kistler, married Marcel Allain on 27 September 1926.