4. Ariel Winter
While better known for her success on "Modern Family" as Alex, Winter has already cultivated a niche for herself within what her agents probably call "genre" material. She's voiced Princess Perdita and Carrie Kelly in various animated DC comics movies, and she's also ventured into video games with roles in some Final Fantasy and Kingdom Hearts releases. She's also had a chance to build her more serious on-camera work with an early role in One Missed Call and a recurring character on the last year or so of "ER."
Above all, Winter would project Ellie's innocence. We can't feel for a teenage girl when she kills a man for the first time unless she actually can show us how out of her depth and overwhelmed she is. Winter can do this. Even via only her voice, that element was present in The Dark Knight Returns, particularly when masquerading as a mutant gang member. And while horror and high drama are parts of her professional past, Winter could certainly use an updated outlet to show off her range.