In the Marvel Cinematic Universe (MCU), Black Widow, played by Scarlett Johansson, is shown to have the ability to calm down the Hulk, portrayed by Mark Ruffalo. This is depicted in "Avengers: Age of Ultron" when she approaches the Hulk during a rampaging moment and manages to establish a connection, helping him revert to his human form, Bruce Banner. While this specific ability to calm the Hulk is unique to the MCU and not a part of the original comic book lore, it has become a memorable and iconic moment in the MCU films.