<P> Prepon co-starred in the romantic comedy Slackers, which is about three best friends who try to scam their way through college and eventually get caught . She was nominated for a Teen Choice Award in 2002 for her role in That' 70s Show . In 2001, she made her film debut in Steve Hanft's musical comedy - drama Southlander with Beck, Beth Orton and Hank Williams III, where she played Seven = Five, a young TV telepathic . In 2004, Prepon worked on the independent drama film The Pornographer: A Love Story . The film tells the story of an obsessive relationship between a director and an actress . </P> <P> Prepon was named one of Stuff magazine's "102 Sexiest Women In The World" in 2002 and one of Maxim magazine's "Hot 100" in 2005 . Prepon had a cameo voice appearance as a United Nations Space Command marine in Halo 2, which was released in 2004 . Her first notable film role came in 2004 with the dark drama Lightning Bug with Bret Harrison, Kevin Gage and Ashley Laurence . Branching into other arenas than acting, Prepon also served as executive producer of the film . She also appeared on an episode of MTV's Cribs in 2003 . </P> <P> In 2005, Prepon co-starred with Misha Collins in the psychological thriller Karla, based on the true story of Paul Bernardo and his wife Karla Homolka, a Canadian couple who kidnapped, sexually abused, and murdered three girls, marking a contrast to her usual lighthearted roles . She was also an executive producer of E! Hollywood Hold'em the same year . Prepon co-starred with Bryan Greenberg as Hannah Daniels in the ABC drama October Road, which debuted March 15, 2007 . The show was canceled by ABC on May 12, 2008, despite strong ratings and a grassroots campaign from the show's fanbase to keep the show alive . In April 2007, she starred in a dramatic short film Once Upon a Time . She also appeared in the 2005 Oxygen original romantic comedy Romancing the Bride . She also was the original voice for Hayley Smith on the Fox animated sitcom American Dad! and voiced her in an unaired pilot . She appeared as Lauren, the long - lost sister of Mary Shannon (Mary McCormack) in the USA Network mystery drama In Plain Sight in the episode "A Frond in Need". On February 5, 2010, it was announced that Prepon signed on to star in Awkward Situations for Men, a pilot on ABC . In 2009, Prepon appeared in the CBS sitcom How I Met Your Mother as Karen, one of the girlfriends of Ted Mosby (Josh Radnor), in the episode "Sorry, Bro". She reprised her role in the episodes "The Front Porch" in 2009 and "Say Cheese" in 2010 . She also appeared in the Fox medical drama House M.D. in the episode "Private Lives". </P> <P> Prepon had been taking directing classes at the Art Center College of Design . She directed a short film, Abide with Me, about a 10 - year - old boy who, "upon bearing witness to his father's murder, is rendered mute ." Prepon stated she plans on making Abide with Me into a feature film . </P>

Who played karen in how i met your mother