Cannes Film Festival: Iran's Zar Amir Ebrahimi wins best actress award
In the film, she plays a journalist trying to solve the serial murders of prostitutes in the holy city of Mashhad.
"I have come a long way to be on this stage tonight," she told the audience at the awards ceremony.
"It was not an easy story, it was humiliation, it was solitude but there was cinema, it was darkness but there was cinema. Now I'm standing in front of you on a night of joy."
Holy Spider, directed by Iranian Ali Abbasi, is inspired by the true story of a working-class man who killed prostitutes in the early 2000s and became known as the "Spider Killer".
Abbassi was denied permission to film in Iran and it was ultimately shot in Jordan.
Ebrahimi became a star in Iran in her early twenties for her supporting role in one of its longest-running soap operas, Nargess.
But her life and career fell apart shortly after the show ended, when a sex tape was leaked online in 2006 which, it was claimed, featured her.
Ebrahimi's character in Holy Spider has also been a victim of lascivious rumours and male predation.
The film suggests there was little official pressure to catch the murderer, who ends up a hero among the religious right.
"This film is about women, it's about their bodies, it's a movie full of faces, hair, hands, feet, breasts, sex – everything that is impossible to show in Iran," Ebrahimi said.
"Thank you, Ali Abbasi for being so crazy and so generous and for directing against all odds this powerful thing."
Cinema, she added, has "practically saved my life".