Reaser was born in West Bloomfield, Michigan and wanted to be an actor from childhood. As the middle child in a trio of sisters, she grew up in rural Milford, Michigan. Her mother (a homemaker), and her father (an attorney turned restaurateur turned substitute teacher) are divorced. Through high school, she worked several odd jobs, including being a caddy at a country club.
Reaser began college at Oakland University in Rochester Hills, Michigan, but after one year yearned to leave the Midwest and expand her horizons. She applied (with her parents' blessing) to the Julliard School of Drama, and was accepted. From Julliard she was awarded a Bachelor's of Fine Arts (B.F.A.) in 1999. She struggled at first, but soon found adequate representation and a part on the daytime drama series, Guiding Light. Since then, she has become an accomplished film, television, and stage actor, landing numerous supporting and leading roles. Reaser appeared as a multi-episode patient named Ava (aka Rebecca) on Grey's Anatomy, and later returned for a few episodes as Alex Karev's mentally unstable girlfriend. She earned a Primetime Emmy Award nomination for Outstanding Guest Actress in a Drama Series for this role. She was also the lead character on the short-lived show The Ex List. In 2008, she played the role of Esme Cullen in the movie Twilight. She returned for the film's sequels, New Moon and Eclipse.
Reaser once appeared in a London stage production for only two audience members, and in preparation for her role on Saved she hung out in an emergency room, researching the behavior of medical staff. In October 2004, Interview magazine hailed her as one of the "14 To Be" emerging creative women. She earned the "Jury Award" at the Newport Beach Film Festival in 2006 for her work in the film Sweet Land, and in 2007 was nominated for an Independent Spirit Award as "Best Female Lead" for the same part.
|2001||Thirteen Conversations About One Thing||Young Woman in Class|
|2002||Emmett’s Mark||Alison Holmes|
|2004||Mind the Gap||Malissa Zubach|
|2005||The Family Stone||Susannah Stone Trousdale|
|2006||Puccini for Beginners||Allegra Castiglione|
|The Wedding Weekend||Julep|
|Grey's Anatomy||Ava/Rebecca Pope|
|2009||The Twilight Saga: New Moon||Esme Cullen|
|Against the Current||Liz Clarke|
|2010||The Twilight Saga: Eclipse||Esme Cullen|
|2011||The Twilight Saga: Breaking Dawn - Part 1||Esme Cullen|
|2012||The Twilight Saga: Breaking Dawn - Part 2||Esme Cullen||November 16, 2012|
Reaser's favorite book from The Twilight Saga is Twilight.
She is listed as a vegetarian.