Made her theatrical debut while a student at the University of Western Australia when she appeared in a performance of the Edward Bond play Early Morning at the UWA's New Dolphin Theatre.
Following her family's move to Australia, she attended Hollywood Senior High School, followed by the University of Western Australia.
In 1996, Greta won an Emmy Award for Outstanding Supporting Actress in a Miniseries or a Special for Tsarina Alexandra in Rasputin.
Her parents divorced when she was four, and her mother returned to England. In 1975, after her mother married Giovanni Carsaniga, the family moved to Perth, Western Australia.
She has two older brothers.
Her father is Luca Scacchi Gracco, an Italian art dealer and painter. Her mother is Pamela Carsaniga, an English dancer and antiques dealer.