Rooney MaraHow You May Know Her: Mara played the (fictional) girlfriend of Mark Zuckerberg in Sony's critically acclaimed Facebook flick The Social Network.
Why You Will Know Her: Mara will star as Lisbeth Salander in The Girl with the Dragon Tattoo, the first of a planned trilogy based on Stieg Larsson's bestselling novels. More established actresses like Natalie Portman, Ellen Page and Scarlett Johansson were reportedly passed over for the coveted gig.
Rosie Huntington-WhitleyHow You May Know Her: In her previous life she was best known for cavorting around in Victoria's Secret underwear alongside Gisele Bundchen and Adriana Lima.
Why You Will Know Her: She stepped to fill Megan Fox's spot in the upcoming Transformers flick, Dark of the Moon. (She has worked with director Michael Bay before on a Victoria's Secret commercial.) Though Fox has since blasted her experience on the movies, it proved a strong launching pad for her and co-star Shia LaBeouf.
Olivia WildeHow You May Know Her: Wilde cut her teeth as Marissa Cooper's lesbian girlfriend on Fox's pop-culture hit The OC, then followed up with another significant small-screen role as Thirteen on Hugh Laurie's House.
Why You Will Know Her: Let the cross-over begin. After gracing the silver screen as Quorra in Disney's winter reboot Tron: Legacy, she'll move on to the Jon Favreau-directed Cowboys and Aliens. Off-screen, her charitable efforts continue to garner admiration and ink.
Asa ButterfieldHow You May Know Him: The 13-year-old Brit starred opposite Emma Thompson in kid flick Nanny McPhee and the Big Bang. His performance drew critical raves, though it fell short of establishing him as a household name.
Why You Will Know Him: He was tapped to star as Hugo in Martin Scorsese's 3-D film adaptation The Invention of Hugo Cabret. The movie is expected to hit theaters in late 2011.
Mia WasikowskaHow You May Know Her: The Australian actress grew both her resume and fan base in 2010, thanks to her work in billion-dollar blockbuster Alice in Wonderland and Sundance darling The Kids are Alright.
Why You Will Know Her: She'll portray the title character in an adaptation of Jane Eyre and a terminally ill teen in Gus Van Sant's highly anticipated Restless.
Justin TimberlakeHow You May Know Him: Chances are you already know Justin Timberlake, the boy-band star turned Grammy-winning solo artist. You may also know Justin Timberlake the tabloid target. Perhaps even Justin Timberlake the beloved Saturday Night Live guest resonates with you.
Why You Will Know Him: Welcome Justin Timberlake the movie star. Come 2011 he'll have two opportunities--Bad Teacher, then Friends with Benefits--to prove his critically acclaimed turn as Sean Parker in The Social Network wasn't a fluke.
Jason ClarkHow You May Know Him: The Australian actor won some stateside fans as Tommy Caffee in Showtime's since canceled Brotherhood. More recently he segued to the big screen as Red in Michael Mann's 2009 flick Public Enemies.
Why You Will Know Him: Clark was cast as the lead in Fox's hotly anticipated midseason cop drama Chicago Code, from Shield creator Shawn Ryan.
Chris HemsworthHow You May Know Him: The Australian actor may look familiar from his work on the big screen (he played George Kirk in JJ Abrams' Star Trek reboot). In addition to other roles down under, he appeared on the Aussie version of Dancing with the Stars.
Why You Will Know Him: Hemsworth has been cast as the title character in Kenneth Branagh's big-screen adaptation of Marvel's Thor. The role will also make him an important part of the upcoming Avengers flick, where he'll have to hold his own against Iron Man's Robert Downey Jr.
Holt McCallanyHow You May Know Him: His previous work includes roles in HBO flick Tyson (he played legendary trainer Teddy Atlas) as well as the big screen's Fight Club and The Losers.
Why You Will Know Him: He has been tapped to star in FX's latest series, the boxing drama Lights Out. With a frame better suited for the boxing ring than the Broadway stage, he will play Patrick "Lights " Leary, a former world champion boxer who is diagnosed with pugilistic dementia and struggles to make a life for his family.
Hailee SteinfeldHow You May Know Her: You don't.
Why You Will Know Her: Newcomer Steinfeld holds her own in the Coen Brother's film True Grit against stars Jeff Bridges, Matt Damon and Josh Brolin. While this is her first big role, it's a good bet that it won't be her last.