Black Widow
Born an orphan, Natalia Romanov was raised as part of the USSR's "Black Widow Ops" program. Trained for espionage, Natalia was the finest agent created by the program, earning the title "Black Widow".
The Black Widow came to America to steal secrets from Stark Industries, leading her into conflict with Iron Man. She would meet and start a romantic relationship with Hawkeye, which caused her to defect from the USSR and become a S.H.I.E.L.D. agent. Now living in America, the Black Widow has been romantically linked to Hawkeye, Daredevil and Iron Man, and has been a member of S.H.I.E.L.D. and the Avengers.