Thora Birch (born March 11, 1982) is an American actress and producer. She made her film debut in Purple People Eater (1988), for which she won a Young Artist Award for "Best Young Actress Under Nine Years of Age", and rose to prominence as a child star with appearances in films such as All I Want for Christmas (1991), Patriot Games (1992) and its sequel Clear and Present Danger (1994), Hocus Pocus (1993), Monkey Trouble (1994), Now and Then (1995) and Alaska (1996).

Her breakthrough role came in 1999 when she played Jane Burnham in the highly acclaimed film American Beauty, for which she earned a BAFTA nomination for Best Supporting Actress. She then starred as Enid in the cult hit Ghost World (2001), earning a nomination for the Golden Globe for Best Actress. In 2003, she received an Emmy Award nomination for playing the title role in Homeless to Harvard: The Liz Murray Story. Her other films include Dungeons & Dragons (2000), The Hole (2001), Silver City (2004), Dark Corners (2006), Winter of Frozen Dreams (2009) and Petunia (2012).

She played Aggie Travers in the revival series episode "The Choice". At 12 years old, she was the youngest actor to play the protagonist in any episode.