Natasha Romanoff / Black Widow
Natasha Romanoff / Black Widow (Scarlett Johansson)
S.H.I.E.L.D. Agent Natasha Romanoff (Natalia "Natasha" Alianovna Romanova), a.k.a. Black Widow, is one of the world's greatest spies and is quite possibly the world's most skilled assassin. Armed with an extensive arsenal of specialized weapons like widow stings and cluster bombs, as well as a vast repertoire of martial arts skills, Romanoff's unique talents makes her one of director Fury's top agents and an integral part in assembling The Avengers. She seems to have a dark history in the films, as Loki mentioned that her ledger was "covered in red." At some point in time Hawkeye had been ordered to kill her, but instead offered her a new life working for S.H.I.E.L.D.
Natasha first shows up in Iron Man 2, using the name Natalia, as Tony Stark’s new assistant. She proves to be very capable and even beat Happy Hogan (Tony Stark’s body guard and friend) in a boxing match. Occasionally she flirts with Tony to get her closer to him. This seems to make Tony suspicious. His suspicions are confirmed when she meets Tony alongside Nick Fury at a restaurant as the Black Widow, revealing she was a double agent. Tony tried to fire her, but at that point had relinquished his rights as CEO of Stark Industries.
As Nick Fury and Tony Stark are talking Natasha injects Tony with a serum that temporarily cures him of a disease he had contrived from the Palladium in his chest. Natasha stayed employed at Stark Industries as Pepper Potts assistant mostly to keep an eye on Tony. At one point Tony shows up as Pepper’s office and Natasha walks in. She was surprised to find that Tony did not reveal her true identity. After Pepper left the room Tony proceeded to grill and compliment Natasha by telling her she is very good at what she does. She gets aggravated at him and after he asks if she can even speak Latin she replies “Drive yourself home or I can have you collected” in Latin.
When Ivan Vanko takes control of War Machine’s suit and attacks Iron Man along with his robot counterparts Natasha springs into action and has Happy Hogan drive her to where Ivan is controlling them. She arrives in her Black Widow uniform and proceeds to take out 11 security guards while Happy is busy with just one. She finds where Ivan was controlling the robots only to find that he is gone. She proceeds to hack and reboot War Machine’s suit allowing Rhodey to take control again. This leads to Iron Man and War Machine defeating Whiplash.
In the Avengers she is first seen interrogating a gang leader but leaves in the middle of the job when she finds out Hawkeye has been compromised. She then uses her persuasive abilities to convince Bruce Banner to join S.H.I.E.L.D. in locating the Tesseract (Avengers)
She uses her skills to manipulate Loki into telling her his intentions to use the Hulk unleash his power inside the Helicarrier in order to weaken the Avengers and later in that battle restores Hawkeye's mind by hitting him really hard on the head.
She manages to take Loki's staff and close the portal he is using to bring the Chitauri to earth.