Scarlett Johansson in 'The Avengers' & 'Iron Man 2'
Although Scarlett Johansson tackled her first action role as the obligatory hot girl in a Michael Bay's 2005 movie The Island, it was her turn as saucy S.H.I.E.L.D. agent Natasha Romanoff, a.k.a. the Black Widow, in 2010's Iron Man 2 that proved she was truly a force to be reckoned with, bashing bad guys alongside Robert Downey Jr.'s Tony Stark/Iron Man. She reprises the role in The Avengers (in theaters May 4), playing the lone female amongst a gaggle of male heroes -- including Iron Man, Captain America (Chris Evans), Thor (Chris Hemsworth), Hawkeye (Jeremy Renner) and The Hulk (Mark Ruffalo) -- out to save Earth from otherworldly villain Loki (Tom Hiddleston).
To hold her own against all that testosterone -- and to be able to slink into her form-fitting black leather suit (which she likens to wearing "sweaty pajamas") -- Johansson had to work out like a beast... and it shows. The actress did many of her own stunts for the action-heavy film, taking out baddies with her fists and some very acrobatic kicks. Not exactly moves she needed for Lost in Translation or The Girl With the Pearl Earring.