Amanda Michelle Seyfried (born December 3, 1985) is an American actress, singer-songwriter and former child model. She began her career as a child model when she was 11 and at 15 she began her career as an actress, starting off with uncredited roles and moving on to recurring roles on As the World Turns and All My Children.
In 2004, Seyfried made her film debut in Mean Girls playing Karen Smith, the ditziest of the so-called "Plastics". Her subsequent roles as a supporting character were in independent films like Nine Lives (2005) and Alpha Dog (2006). She also had a recurring role in the UPN TV show Veronica Mars (2004-2006). Between 2006 and 2010, she landed a lead role on HBO's popular television series Big Love. After that, Seyfried appeared in her breakthrough and first leading role as Sophie Sheridan in the 2008 musical feature film Mamma Mia!. Other recent appearances include successful leading roles in Jennifer's Body (2009), Chloe (2010), Dear John (2010), Letters to Juliet (2010), and Red Riding Hood (2011).
In 2009 she started dating her Mamma Mia! co-star Dominic Cooper. The couple broke up in May 2010. She then began a relationship with Ryan Phillippe.