An erotic actor or erotic actress or a porn star is somebody who appears in pornographic movies. Many actors/actresses may appear nude in films (usually rather briefly) or on stage but even if they depict sexual behavior they are not considered erotic actors. Most erotic actors use stage names.
... Stiva who encourages him in this plan, but, later that evening, Kitty rejects him in the expectation that Vronsky is about to propose to her.
The following morning ...