Earlier this week, the first in a series of character posters from the highly-anticipated action-packed sequel Avengers: Age of Ultron debuted, straight from the Twitter pages of stars Robert Downey Jr. (Iron Man) and Mark Ruffalo (Hulk). Today, Samuel L. Jackson debuted two more one-sheets for his character Nick Fury and Scarlett Johansson's Black Widow from his own Twitter page.