6. Maria Hill
S.H.I.E.L.D. Agent Maria Hill was played by Cobie Smulders in The Avengers. She will be reprising her role in Captain America: The Winter Soldier next year, and later this fall in the pilot episode of Agents of S.H.I.E.L.D. Hill will have a recurring role in the MCU (as evidenced by Smulders's 7-picture contract), and becomes the director of S.H.I.E.L.D. in the comics. Based on how little we know of her from the small part she played in The Avengers, she could easily be the focus of a One Shot. The story possibilities with Maria Hill are endless. Origin story? Standalone mission? Marvel could easily dive into her story and backstory and save themselves from needing to devote precious screen time to the task in their feature films.