Charles Marlow
Marlow's name may be inspired by the Elizabethan playwright Christopher Marlowe. Conrad's father was a translator of William Shakespeare who doubtless would have known of Marlowe's work as well. Some intertextual interpretations of "Heart of Darkness" have suggested that Marlowe's "The Tragical History of Doctor Faustus" may have influenced Conrad. Charles Marlow describes a character as a "papier-mache Mephistopheles", a reference to the Faust legend. Marlow's and Kurtz's journey up the Congo River in "Heart of Darkness" also has similarities to another work by Marlowe, "Dido, Queen of Carthage", in which Aeneas is stranded on the shore of Libya and meets the African queen Dido.
Stefan Schnabel
When Mercury Productions moved to the West Coast, Schnabel was one of the actors Welles cast in "Heart of Darkness", the film he first proposed for RKO Pictures before settling instead on "Citizen Kane". After elaborate pre-production the project never reached production because Welles was unable to sufficiently trim its budget to compensate for lost revenue in the wartime overseas market.