Nina Romanova (Earth-5171)

Nina Romanova is a cold-blooded assassin and spy who goes by the name of Black Widow. She was originally an agent of the KGB, often working with her younger sister, Ana. Nina and Ana where drugged and experimented on at a young age in an attempt to create the perfect assassin. She soon became regarded as a master spy and one of the world's greatest assassins. She later became a member of S.H.I.E.L.D. She often clashes with Ana, and has a rivalry with her.