Robert Downey, Jr.’s original Iron Man megahit led to a string of Marvel-based movies starring heroes who, next month, will unite in The Avengers, directed and co-written by Joss Whedon. And one of those heroes – specifically, a heroine – made her first appearance here, in a supporting role in this 2010 Iron Man sequel. She’s Natalie Rushman, a.k.a. Natasha Romanoff, a.k.a. the Black Widow – all three of them played by Scarlett Johansson.