Nathalie, Secret Agent (French: Nathalie, agent secret US: Atomic Agent) is a 1959 French-Italian comedy thriller film directed by Henri Decoin and starring Martine Carol, Félix Marten and Darío Moreno. It is a sequel to the 1957 film Nathalie starring Carol in the title role with Dany Saval also reprising her role as Pivoine. It was shot at the Billancourt Studios in Paris. The film's sets were designed by the art director Robert Clavel.