Collette was raised in the Sydney suburb of Blacktown.At age 16 she accepted a scholarship from the Australian Theatre for Young People (1989), and she later briefly attended the National Institute of Dramatic Art. She dropped out to accept her first film role, in Spotswood (1992), opposite Anthony Hopkins and Russell Crowe. She made her first significant foray into theatre as Sonya in the Sydney Theatre Company production of Anton Chekhov’s Uncle Vanya (1992).

Her rollicking turn as the overweight, unhappy title character in Muriel’s Wedding (1994) brought Collette to international attention, and a spate of supporting roles in films, including Emma (1996), Clockwatchers (1997), and Velvet Goldmine (1998), followed.

Her performance in The Sixth Sense (1999)—in which she evinced the distress of a mother whose son can see ghosts—brought her an Academy Award nomination for best supporting actress. She received a Tony Award nomination for The Wild Party (2000), her Broadway debut. Though occasionally relegated to one-dimensional roles in thrillers such as Shaft (2000) and Changing Lanes (2002), Collette won accolades for the gravitas she brought to ancillary characters in About a Boy (2002) and The Hours (2002).

Her musical talents were brought to the fore in Connie and Carla (2004), a comedy in which she played a woman hiding from the mob by impersonating a male drag performer. Though that film was panned, Collette eked positive notices for the ostensibly slight In Her Shoes (2005), in which she was featured as the dowdy sister to Cameron Diaz’s promiscuous wastrel.

Her role in the ensemble comedy Little Miss Sunshine (2006), in which she played the matriarch of a dysfunctional clan attempting to shepherd its youngest member to a beauty pageant, earned her a Golden Globe Award nomination for best supporting actress. She earned another Golden Globe nomination and an Emmy Award nomination for best supporting actress in a television movie for Tsunami: The Aftermath (2006). Collette took supporting roles in the dramas Evening (2007) and Towelhead (2007) and the horror film Fright Night (2011). She then starred in the offbeat Australian comedy Mental (2012) before playing Alfred Hitchcock’s personal assistant in the biographical Hitchcock (2012).

Collette played the mother of a family threatened by a demon during the holidays in the horror comedy Krampus (2015). She appeared in several low-rated films throughout 2017, but her movies from 2018, which included the horror flick Hereditary and the feel-good drama Hearts Beat Loud, garnered more-favourable reviews.

Collette was then cast in Velvet Buzzsaw (2019), a horror parody wherein artworks seemingly exact revenge on those who profited from a deceased painter’s oeuvre. In 2019 she also appeared in Knives Out, a comedic whodunit involving the death of a mystery writer.

According to britannica.com