Sofia Vergara wears a simple navy strapless Vera Wang dress with a fishtail hem, diamond chandelier earrings and a smooth glossy 'do.

Zooey Deschanel keeps things "adorkable" by channeling Marlo Thomas' That Girl. Plus: We love her tuxedo-painted fingernails.

Amber Riley looks gorgeous in an asymmetrical strapless gown with a sweetheart neck.

Diane Lane is flawless (and ageless) in a short-sleeved gold beaded dress.

Evan Rachel Wood takes a risk with a plunging neckline and a stunning deep greenish-black color that pops against her fair skin.

Ariel Winter looks adorable in a tea-length purple dress with a black tulle underskirt.

Chris Colfer is dapper in a black suit and matching skinny tie.

Rooney Mara keeps her stark black Girl with a Dragon Tattoo 'do, which matches her V-neck mermaid gown that has daring cutouts.

Octavia Spencer is in another Tadashi gown and looks stunning in a silvery number that has applique on top and a satin skirt.

John Krasinski stands out from the crowd in a midnight blue Prada suit while his wife Emily Blunt stuns in bright green.

Kyra Sedgwick goes bold in a sexy bright red dress with cut-outs showing her new tattoo.

Angelina Jolie wears a black halter Jenny Packham draping gown with vintage jewels while Brad looks sharp in his suit and tie.

Viola Davis is a standout in a bright white gown with a sweetheart neckline and gold detailing.

Rihanna is capital "S" sexy with this navel-grazing low-cut neckline, high slit and wavy blonde locks.

Carrie Underwood looks sophisticated in a long-sleeved glittery dress with her hair pulled back in a loose bun.

Adele, glam with a striking red lip, is stunning in a floor-length black sequined dress that cinches at the waist.

We're not sure why Kate Beckinsale is there, but she looks gorgeous in this short satin one-shouldered mini-dress.

Aside from that head of hair, Kelly Osbourne is appropriately glam and full of glitter in her one-shoulder gown that gathers at the waist and drapes below.

Kathy Griffin is surprisingly low-key in understated jewels and an ivory form-fitting dress that ruches across her midsection.

Lady Antebellum's Hillary Scott is chic in this two-tone black and purple strapless gown and pin-straight locks.

Alicia Keys is rocking a front bun with a black dress and chunky gold necklace, and her husband Swizz Beatz is looking pretty sharp in a purple velvet tux jacket and matching bowtie.

Gwyneth Paltrow looks chic in a simple white Tom Ford gown with a cape that covers her shoulders.

Jennifer Lopez has perfected the extremely low-cut gown, and pulls it off again in white stripes that gather in the center.

Penelope Cruz channels Old Hollywood in a lavender ball gown with slicked back hair.

Cameron Diaz’s gown is simple on the top, but flirty and fun on the bottom with flowing handkerchief-style ruffles lined with beads.

Emma Stone is gorgeous in a high-necked cranberry-colored halter gown that cinches at the waist and then drapes to the floor.

Natalie Portman stands out in a red polka-dot dress with a chunky diamond necklace.

Milla Jovovich sparkles in a striking, one-shoulder Elie Saab gown.

Bridesmaids' Ellie Kemper chooses a sparkly copper- and golden-beaded strapless gown that complements her reddish-brown locks — which could use a trim in the bangs.

Jessica Chastain epitomizes the classic, glamorous Hollywood starlet in her sweetheart-neck gown.

Leslie Mann looks stunning in her flowing, navy strapless gown that has pizazz with the sparkly middle.