Today, what is sure to be the Snakes on a Plane blockbuster hit of the year opens: Obsessed, starring the increasingly luminous Beyoncé Knowles. It's her first psychological thriller and first serious acting role in which she does not play a singer. So it marks a momentous occasion in Beyoncé's life, and therefore in history. And Beyoncé arrived to the New York premiere last night like she knew it, dressed in a dramatic black Balmain dress with sweeping train. Now, since we've been obsessed with this movie — it being Beyoncé's first psychological thriller — for weeks now (watch the preview before you judge), it only makes sense for us to obsess over the clothes. Our thoughts on Beyoncé's Balmain lie in the slideshow. As do our thoughts on what Tinsley Mortimer, Ali Larter, Chanel Iman, and more wore.