Natalie Portman's first lesson in Hollywood stardom was quite disturbing.

The Oscar-winning actress, now 36, spoke to the Women's March audience Saturday in Los Angeles. She recalled her first fan experience, after playing Mathilda in Luc Besson's 1994 classic "Léon: The Professional."

Here's part of Portman's speech addressing "sexual terrorism":

"I turned 12 on the set of my first film, 'The Professional,' in which I played a young girl who befriends a hitman and hopes to avenge the murder of her family. The character is simultaneously discovering and developing her womanhood, her voice, and her desires. At that moment in my life, I too was discovering my own womanhood, my own desires, and my own voice.

I was so excited at 13 when the film was released and my art would have a human response. I excitedly opened my first fan mail to read a rape fantasy that a man had written me. A countdown was started on my local radio show to my 18th birthday, euphemistically the date that I would be legal to sleep with. Movie reviewers talked about my budding breasts in reviews.

I understood very quickly, even as a 13-year-old, that if I were to express myself sexually, I would feel unsafe. And that men would feel entitled to discuss and objectify my body, to my great discomfort. So I quickly adjusted my behavior. I rejected any role that even had kissing scene and talked about that choice deliberately in interviews. I emphasized how bookish I was, and serious I was. And I cultivated an elegant way of dressing. I built a reputation for basically being prudish, conservative, nerdy, serious, in an attempt to feel that my body was safe and that my voice would be listened to.

At 13 years old the message from our culture was clear to me. I felt the need to cover my body, and to inhibit my expression and my work in order to send my own message to the world, that I'm someone worthy of safety and respect...."

Watch more in her full speech:

The timing is disquieting, since some photos had just gone viral, suggesting 13-year-old "Stranger Things" star Millie Bobby Brown looks a lot like a younger Natalie Portman. Is history just repeating itself? David Harbour (Chief Hopper on "Stranger Things") told People movements like Time's Up and #MeToo and the women's marches will help shape a better story for his young costar. "I think Millie will grow up in a better Hollywood than we did."

Natalie Portman will next be seen in "Annihilation," which opens February 23.

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