- Source of Wealth: Film and Television
- Age: 33
- Birth Place: New York City, New York, U.S.
- Height: 5′ 4″ (1.63 m)
- Weight: 120 lbs (54.5 kg)
- Marital Status: Single
- Full Name: Olivia J. Thirlby
- Nationality: American
- Date of Birth: October 6, 1986
- Ethnicity: Ashkenazi Jewish and English
- Occupation: Actress
- Education: Friends Seminary, French Woods Festival of the Performing Arts, Royal Academy of Dramatic Art
- Children: None
Best known as Leah in the 2007 film titled Juno, Olivia Thirlby is an American actress with a personal net worth amounting to $2 million. She is also known for her role as Cassandra Anderson in Dredd and Natalie in The Darkest Hour.
In June 2008, she was named as Hollywood’s New Wave by the Vanity Fair Magazine. While still in high school, she was offered a role in The Secret but her TV and film debut only came in 2006 when she appeared on Kidnapped and United 93 respectively.
Subsequently, Olivia Thirlby began appearing in a number of film, stage and TV projects which include The Wackness, Pineapple Express, Farragut North, Bored To Death, The Manners of Madness, The Movie, The No Game, Nobody Walks and The Other Side.