
In 2004, Seyfried made her film debut in Mean Girls playing a supporting role. She then went on to other films including Nine Lives (2005) and Alpha Dog (2007). In 2008, after landing a lead role on a popular television series (Big Love in 2006) Seyfried appeared as Sophie Sheridan in the musical feature film Mamma Mia!. Other recent notable appearance include a supporting role in Jennifer's Body in 2009, and one of the two lead roles in Dear John the following year. She currently has three films in production.
Early life:
Seyfried was born Amanda Michelle Seyfried in Allentown, Lehigh County, Pennsylvania, United States on December 3, 1985. Seyfried's mother, Ann (née Sander), was an occupational therapist, and her father, Jack Seyfried, was a pharmacist. Seyfried has one older sister; Jennifer Seyfried, who is a musician in the Philadelphia organ-driven rock band "Love City". Amanda graduated in 2003 from Allentown's William Allen High School.

In 2006, Seyfried began a relationship with actor and musician Jesse Marchant; the relationship ended after two years in 2008. In 2008, Seyfried began dating her Mamma Mia! co-star, Dominic Cooper. In 2008, Seyfried was ranked #65 on the list of "The Annual Independent Critics List of the 100 Most Beautiful Famous Faces From Around the World" and was also placed #5 in Moviefone's "25 Under 25: Hollywood's Hottest Young Stars". The following year the United Kingdom Glamour.com (of Glamour magazine) ranked Seyfried at the #17 spot as one of the "30 Hottest and Sexiest Stars Under 30". In 2009, People Magazine ranked Seyfried #4 in the Most Beautiful 2009 - Beautiful at Every Age.

Seyfried's break-through role was portraying one of the main characters, Sarah Henrickson, in the HBO television series entitled Big Love. On the television show, which centers on a fictional fundamentalist Mormon, Seyfried plays Sarah, Bill and Barb's first daughter who is struggling with her father's polygamous faith. Big Love premiered in the United States on March 12, 2006 and HBO confirmed that the show was renewed for a fourth season – which was filmed in August 2009, and is set to be premiered on January 10, 2010. To date, Seyfried has appeared in all thirty-five episodes of the show over the course of the shows three seasons. In December 2009, HBO confirmed that Seyfried would return to the shows fourth season, but that it would be her last because Seyfried had wanted to focus on her film career and up-coming projects.
Following the success of Big Love, Seyfried had a supporting role as Zoe in the 2008 film Solstice. That year, Seyfried also co-starred alongside Meryl Streep in Mamma Mia!, a romantic comedy film adaptation of the 1999 musical of the same name. In the film, Seyfried portrays Donna's daughter and Sky's fiancée; the film was Seyfried's first film as a lead role. With the worldwide revenue of 609 million – compared to its 52 million budget – the film was a box office success; the film is also the fifth highest grossing film of 2008 and currently is the 49th highest grossing film of all time. Her musical performance in Mamma Mia! is available on the film's soundtrack, for which she recorded five songs. As part of promotion for both the film and its soundtrack, Seyfried recorded a music video of the song, entitled "Gimme! Gimme! Gimme! (A Man After Midnight)".

Seyfried is set to appear as the title character in Chloe; the film is set to be theatrically released on March 19, 2010. Chloe, which Seyfried co-stars alongside Liam Neeson and Julianne Moore, had originally premiered at the Toronto Film Festival in September 2009. In the film, Seyfried plays Chloe, a woman who was hired to 'test' a husband because his wife feels that she cannot trust his fidelity; negative consequences ensue after the beginning of the arrangement. In September 2009, Seyfried became attached to the film entitled Marmaduke. The film, which co-stars George Lopez and Fergie, is based on a popular comic strip "Marmaduke". The film will be a mix of live action and CG-animated creatures. Seyfried was cast in the film as the voice of "Mazie". The movie was filmed in the summer of 2009 and is currently scheduled to be released on June 4, 2010.
Seyfried co-starred alongside Channing Tatum in the film adaptation of the novel of the same name that was written by Nicholas Sparks, entitled Dear John. The film was released on February 5, 2010. Seyfried has written and recorded a song titled Little House, one of the official soundtracks of Dear John. Seyfried is also set to appear in the film entitled Letters to Juliet; the film is a film adaptation of the book of the same name by Lise and Ceil Friedman. The film centers on a couple (Seyfried and García) who discover a letter written to Juliet Capulet. The film is set to be released on May 7, 2010. In late January 2009, Seyfried became attached to appear in Myriad Pictures' adaptation of Oscar Wilde's comedy "A Woman of No Importance". The film, that Seyfried co-stars alongside Annette Bening and Sean Bean, is set to be released in 2011. In the film, Seyfried will play the love interest to the womanizer Lord Illingworth at an "awfully posh upper-class party at the family's pile in the English countryside."