Gellar's major break came in 1992, when she starred in the teen soap opera Swan's Crossing, after which she starred in the soap opera All My Children, playing the conniving character Kendall Hart, the long-lost daughter of character Erica Kane (played by Susan Lucci). In 1995, at the age of 18, she won a Daytime Emmy Award for Outstanding Younger Leading Actress in a Drama Series.

Gellar left All My Children in 1995 and landed the lead in the TV series Buffy the Vampire Slayer, created by Joss Whedon, as a teenager burdened with the responsibility of fighting a number of mystical foes, with the aid of a group of friends and her Watcher (a teacher of sorts). The show was well received by critics and audiences alike, and, throughout its seven seasons and a total of 144 episodes, Buffy, and Gellar along with her, became cult icons in the United States and the UK.

Gellar has appeared on the covers of Cosmopolitan, Glamour, FHM, Rolling Stone, and dozens more. She was in some Got milk? ads, and is a model for Maybelline. She was featured on Maxim's Hot 100 list in 2002, 2003, and 2005, and in FHM's 100 Sexiest Women of 2005. In 1998, she was named one of People Magazine's "50 Most Beautiful People (in the World)."

With continued success on Buffy, she attempted to capitalize on her television fame to create a career for herself in motion pictures, with intermittent commercial success. After roles in the popular thrillers I Know What You Did Last Summer and Scream 2 by Wes Craven, she starred in the film Simply Irresistible. This film featured a magical crab and borrowed heavily from Like Water for Chocolate.

Her next film was Cruel Intentions, a modern-day retelling of Les Liaisons Dangereuses; this movie included a lesbian kiss between Gellar and Selma Blair. In 1999, she also appeared in the Stone Temple Pilots music video Sour Girl.

She then played a lead role in James Toback's critically unsuccessful Harvard Man (2001), followed by box office success as Daphne in Scooby-Doo, a live-action adaption of the cartoon series. Despite being universally panned by critics, the movie was highly popular with audiences, and she also appeared in the movie's sequel, Scooby-Doo 2: Monsters Unleashed (2004).

On September 1, 2002, Gellar and actor Freddie Prinze, Jr. were married in Jalisco, Mexico. Adam Shankman, with whom Gellar had worked on Buffy, officiated at the nondenominational wedding. The couple had met several years before, while filming I Know What You Did Last Summer [1] and were engaged in April 2001.

In 2004, David Wirtschafter, the president of the William Morris Agency, which represented Gellar, told The New Yorker that the success of Gellar's low-budget film The Grudge (a remake of the Japanese horror film Ju-on: The Grudge) "takes our client Sarah Michelle Gellar, who now is nothing at all, and . . . makes her a star, potentially. Suddenly, the Sarah Michelle Gellar space is meaningful." The remark led Gellar to terminate her association with the agency.

In 2005, Gellar starred in The Return with Peter O'Brien and Sam Shepard and, the same year, made Southland Tales.

In 2006, she made The Air I Breathe with co-stars Kevin Bacon, Brendan Fraser, Andy Garcia, and Forest Whitaker in Mexico City. She also reprised her role as Karen Davis in a cameo for The Grudge 2. She will appear briefly in The Grudge 2, to pass the curse onto her sister in the film, played by Amber Tamblyn.

Currently, Sarah is starring in A Girl's Guide to Hunting And Fishing, based on the book of the same name, with co-star Alec Baldwin.

Gellar is expected to start filming Alice, based on the game from American McGee in 2006. Alice is expected to be released summer 2007.

She has a total of 8 movies in different stages of production as of this moment.

Credit to Wikipedia