<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> 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>
who played karen in how i met your mother
who played karen in how i met your mother
Prepon
Prepon