First appearing in Marvel Comics in the 1960s, Natasha Romanoff, a.k.a. Black Widow, was introduced to movie audiences in Iron Man 2 (2010). Her character has grown in popularity with subsequent Marvel films, and fans have been vocal about wanting to see Black Widow in a titular role. Romanoff has potent appeal: a strong female character who is not defined by her looks or her romantic relationships, with the skill set of a veteran spy first...