Home and Away actress Jessica Falkholt has had her life support turned off after she was left in intensive care following a crash.
A message on the show's official Twitter feed said: "Rest in peace, beautiful Jessica."
According to Australia's Daily Telegraph, the 29-year-old's life support was switched off on Thursday, a day after a funeral was held for her sister Annabelle, 21, and parents Vivian, 60, and Lars, 69, in the Sydney suburb of Concord.
Lars and Vivian died instantly, and Annabelle passed away in hospital three days later.
Jessica remained in a coma, despite undergoing surgery several times.
The driver of the other car involved, 50-year-old Craig Whitall, also died instantly.
The family had been returning to the city after a brief holiday when the crash happened on the Princes Highway near Sussex Inlet.
Speaking at the funeral, Vivian Falkholt's brother, Paul Ponticello, thanked the emergency services and four civilian rescuers who "risked their own safety to drag both Annabelle and Jessica from the wreckage just before the vehicles exploded in flames," The Sydney Morning Herald reported.
Falkholt, who graduated from Australia's National Institute of Dramatic Art, played Hope Morrison on Home and Away for several months in 2016.
The drama's broadcaster, Network Seven, said of Jessica in a statement last month: "Although her time on set was brief, once a part of the Home and Away family, always part of the family."
Her family has asked for privacy.