Black Widow (Earth's Mightiest Heroes)

Natasha Romanoff, codenamed Black Widow, is a false antagonist and one of S.H.I.E.L.D.'s best agents, formerly partnered with Agent Clint Barton (Hawkeye). On the orders of Director Nick Fury, she pretended to betray S.H.I.E.L.D. to join the terrorist organization HYDRA where she became one of Baron Strucker's lieutenants undercover.