Emma Watson says she was "so angry" when a hoax website claimed it was going to publish naked pictures of her.
Speaking at an event for International Women's day, the Harry Potter star says the threats made her even more keen to speak up on gender equality.
"I knew it was a hoax," she said.
"I knew the pictures didn't exist, but I think a lot of people that were close to me knew gender equality was an issue but didn't think it was that urgent, that it was a thing of the past."
She said she was targeted after giving a speech at the UN.
"When they saw that the minute I stood up talking about women's rights I was immediately threatened, I think they were really shocked, my brother was particularly upset.
"This is a real thing that's happening now, women are receiving threats.
"I was raging, it made me so angry, I was like, 'This is why I have to be doing this.' If anything, if they were trying to put me off it, it did the opposite."
Part of her work as a UN Women Goodwill Ambassador involves fronting the He For She campaign, which calls for men to support gender equality.
"He For She is about men coming to support women for femininity and for feminine qualities, because they are currently valued less in our society.
"Femininity needs to be embraced wherever it is... whether it be in a man or a woman or a non-conforming gender person."
She describes how the "movement" also belongs to her support for LGBT communities and trans people.
"My specific mandate is to advocate for women and girls but I also understand that these oppressions are interlocking, mutually reinforcing. Inter-sectionality is a really important word here.
"We need to be supporting each other, I hope they feel this is their movement, because it is."
Talking to Greg James at a live question and answer session in Facebook's London headquarters, she said: "Our society in general devalues the she, I mean the qualities that are associated with the feminine that are found in all of us.
"There's this imbalance, this distortion that is just hindering our progress, it's causing discord, violence and fear the world over.
"It's uncomfortable, it's awkward to acknowledge there is a problem, but we need to understand we are complicit.
"Another anecdote is that a lot of the criticism I have had in my life, some of the harshest moments have been comments from other women.
"It's not enough to ask men to come and support us.
"We really need to support each other, we really do. So, I guess I would say be brave enough to acknowledge that things are not there yet and support each other."
As a film star and a model, Watson is better paid than most and acknowledged this in her answer on the issue of equal pay "stagnating" and how much she made in comparison to her Harry Potter co-stars.
"I wouldn't dream of complaining about my financial circumstances, but yes, it is a big problem in my industry, it is a huge problem that needs to be addressed," she said.
She also said that maternity leave should not affect how much women should be paid.
"Maternity leave in this country is around two months and I don't think in the grand scheme of things that is going to hinder a women from achieving, or being incredibly effective, in whatever her field is."
Describing her role model, she went for the "obvious choice" - her mum.
"She was a single mother and a type one diabetic, so to see her strength and resilience was really inspiring growing up," she said.
"I think she instilled in me in my teenage years when I was feeling very insecure, that what I was thinking, doing, saying, were infinitely more important than my physical appearance.
"She really encouraged me to be an individual. I remember her being thrilled when I got my first detention because she was really worried I was going to be a bit straight-laced."