Gustave was portrayed by Richard Katz in Agatha Christie's Poirot, though in this continuty, the title Marrascaud belonged to someone else entirely.
In original story
Poirot takes a funicular to the mountain-top hotel of Rochers Neiges. Poirot introduces himself to Gustave tells Poirot that in fact, he is M. Drouet, a police inspector. They discover that before Gustave,
Poirot announces that Gustave is not Drouet but Marrascaud. It was "Robert" who was Drouet; Marrascaud killed him and took his place. We learn that during his first night in the hotel, Poirot did not drink his coffee, as he suspected it was drugged, and actually witnessed Gustave entering his room, rifling his pockets, and finding the note from Argenteui.
In Agatha Christie's Poirot
- Main article: Alice Cunningham
Marrascaud appeared in The Labours of Hercules, the third episode in the thirteenth season of Agatha Christie's Poirot, as its main antagonist. The episode was a loose adaptation of the short story collection, mainly The Erymanthian Boar and The Capture of Cerebus.
Unlike in the original stories, the titular Labours are not undertaken by Poirot as cases, but rather refer to a series of paintings that are stolen by Marrascaud, the main villain; the title is also symbolic of Poirot's path to redemption after his plan to snare Marrascaud leads to the senseless murder of an innocent girl, Lucinda LeMesurier.
The most significant departure from the source material is the change in Marrascaud's identity; in the novel, it is Gustave who is Marrascaud, but in the adaptation, it is Alice Cunningham, the daughter of Countess Vera Rosakoff, and Gustave was one of her two accomplices (along with Dr. Lutz) and a major antagonist of the episode, instead of the main antagonist.
In this adaptation, Gustave had committed suicide to keep the real Marascaud's identity hidden.