Summer Movies 2012: Rihanna, Cobie Smulders, Diego Boneta And 9 Other Breakout Stars

Before last summer, Jessica Chastain and Michael Fassbender were just a couple of young actors trying to make it in the crazy world of Hollywood. Now -- following the successes of "The Help" and "X-Men: First Class," respectively -- Chastain and Fassbender are both A-listers, working with the likes of Robert Downey Jr., Brad Pitt and Angelina Jolie. Summer movies: where stars are made.

So! Which actors are sitting on the verge of a breakout as this year's crop of summer movies arrives? Allow HuffPost Entertainment to offer you some options. Ahead, 12 potential summer breakout stars -- from Cobie Smulders to Luke Kirby.

PHOTOS: Summer 2012 Breakout Stars