Chris Hemsworth, Chris Evans, Robert Downey Jr., Jeremy Renner, Scarlett Johansson, and Mark Ruffalo will forever be known as the Avengers, but they didn't always have superhero status. In honor of "Avengers: Age of Ultron" hitting theaters Friday, this week's #TBT is throwing it back to photos of the stars before they stepped into the Marvel universe. Check out pics of the cast from early in their careers and see how much they've changed over the years.