
Tyler achieved international recognition as a result of her portrayal of Elf maiden Arwen Undómiel in the The Lord of the Rings films. She has appeared in an eclectic range of films, including the 2004 comedy Jersey Girl, the indie film Lonesome Jim (2005), the drama Reign Over Me (2007) and big-budget studio films such as Armageddon (1998), The Strangers (2008) and The Incredible Hulk (2008).
Since 2003, Tyler has served as a United Nations Children's Fund (UNICEF) Goodwill Ambassador for the United States, and as a spokesperson for Givenchy's line of perfume and cosmetics. Tyler married musician Royston Langdon of the band Spacehog in 2003; they have one son, Milo, born December 14, 2004. The couple announced their separation in May 2008.

Tyler was born Liv Rundgren at Mount Sinai Hospital in New York City, New York. She is the first-born daughter of Bebe Buell, a model, singer, and former Playboy Playmate (Miss November 1974), and Steven Tyler, the lead singer of Aerosmith. Her mother named her after Norwegian actress Liv Ullmann after seeing Ullmann on the cover of the March 5, 1977, issue of TV Guide. She has three half-siblings: Mia Tyler (born 1978), Chelsea Anna Tallarico (born 1989), and Taj Monroe Tallarico (born 1992). Her maternal grandmother, Dorothea Johnson, founded the Protocol School of Washington.
At birth, Buell claimed that rock star Todd Rundgren was Tyler's biological father. Tyler discovered her true parentage at age nine. She discovered that she was Steven Tyler's daughter after meeting him and noticing a resemblance she shared with his other daughter, Mia. When she asked her mother about the similarity, the secret was revealed. The truth about Tyler's paternity did not become public until five years later, in 1991, when she changed her name from Rundgren to Tyler, but kept the former as a middle name. Buell's alleged reason for the initial decision was that Steven was too heavily addicted to drugs at the time of her birth. Since learning the truth about her paternity, Liv and Steven have developed a close relationship. They have also worked together professionally, once when she appeared in Aerosmith's music video for "Crazy" in 1993 and again when Aerosmith performed many of the songs in the film Armageddon (1998), in which Tyler starred.

Personal life:
Tyler dated actor Joaquin Phoenix from 1995 to November 1998; the couple met on the set of Inventing the Abbotts. In 1998, she began dating British musician Royston Langdon of the band Spacehog. Tyler and Langdon became engaged in February 2001, and got married in Barbados on March 25, 2003. On December 14, 2004, she gave birth to a son, Milo William Langdon. On May 8, 2008, the couple confirmed through representatives that they would be separating but remain friends. In an interview with The Daily Telegraph, Tyler revealed that her separation from Langdon led her to move to Los Angeles, explaining that it was hard to be in the New York home they shared.
Tyler is an active supporter of the charitable United Nations Children's Fund (UNICEF). She was appointed as a Goodwill Ambassador for the United States in 2003. In November 2004, she hosted the lighting of the UNICEF Snowflake in New York City. Tyler also served as spokesperson for the 2004 Givenchy Mother's Day promotion, in support of UNICEF's Maternal & Neonatal Tetanus (MNT) campaign.Since 2004, she has donated to the Women's Cancer Research Fund to support innovative research, education, and outreach directed at the development of more effective approaches to the early diagnosis, treatment and prevention of all women's cancers. In October 2007, Tyler, along with her mother, Bebe Buell and her grandmother, Dorothea Johnson, helped launch the Emergen-C Pink energy drink, in which the event was in honor of Breast Cancer Awareness month.
She is good friends with designer Stella McCartney, model Helena Christensen and actresses Kate Hudson and Gwyneth Paltrow. Tyler was formerly a vegan, but has since begun to eat meat. In 2003, she became the spokesperson for Givenchy perfume and cosmetics; in 2005 the brand named a rose after her, which was used in one of its fragrances. In 2009, Tyler signed on for two more years as Givenchy spokesperson.