2. Elle Fanning
Easily the best performance in Super 8, including the adults, Fanning has a preternatural poise that makes her stand out from other actors her age. It wasn't enough to convey fear and wonder at the strange happenings in J.J. Abrams' ode to E.T. and Close Encounters of the Third Kind; Fanning showed the very essence of a Spielbergian child character in her emotional independence.
And like Fanning's princess from Maleficent Ellie is very much afraid and vulnerable, but she is also iron-willed. There is room for her to ebb and flow in the moments she can control her dread and those where she tries to deflect it through her precocious cussing and teenage cynicism. While it is always important for a character to appear strong, it's just as important for the actor to let the cracks in the armor show so that we care.