"Obviously, for the character, it's a very traumatic experience, because it's a violence visited upon her," explains the elfin-like 24-year- old. "But, for me, it was actually kind of wonderful to throw vanity away for a little bit.
"As a woman, you're always expected to be primping and preening yourself, so this was a pretty nice opportunity to not have to think about that sort of stuff for a little while at least.
"As a public female, you so often objectified, whether you want to be or not in all those magazine rankings of women, as if they're cars or something. If I could avoid any of those things, which of course you have absolutely no say in, I would in a second.
"On the other hand, I would be happy to do nudity in a film that was appropriate, if only I didn't know that it would end up on a porn site! That's what keeps me from doing it. If a character goes through something that a woman goes through, then I'll play it."
Blurred
She was born in Jerusalem, the only child of a doctor father and an artist mother, who still acts as her agent. She left Israel for Washington, DC, when she was still very young and her family finally settled in New York, where she was discovered by an agent in a pizza parlor at the age of 11. She was pushed towards a career in modelling, but decided that she would rather pursue a career in acting and made her film debut just a couple of years later in the Luc Besson film, Léon, in which she starred as Matilda, a 12-year-old orphan who melts the heart of Jean Reno as a hard-bitten hitman. Controversially, the film blurred the precise nature of her relationship with her menacing mentor.
"Being an only child, I spent so much time around adults, because my parents always took me with them, so I knew how to talk to grown-ups and pretend to be grown up," she remembers. "But I wasn't. I had a strong awareness of how to flirt and how to be shocking, as little girls do."
There's something of a wink to that precocious sexuality in a V For Vendetta scene in which she has to dress up in pigtails and a pink baby-doll outfit in order to trap a paedophile churchman.
"Oh, sure, although that scene was in the original comic novel, that parallel was evident early on," she laughs.
"The fact that I can still look like a kid, that I don't really look much older than I did 12 years ago probably can be taken advantage of." She also lets it slip later that her favourite book is Vladimir Nabokov's Lolita.
Interesting
Clearly, Portman is more than just another airhead trading on the way she looks. After graduating with honours from her high school, she studied psychology at Harvard University and now avows that any role she accepts "has to be something that's going to be as interesting as school was for me."
After three films as Queen Amidala in George Lucas' Star Wars prequels, then an Oscar-nominated turn in Mike Nichols' film version of Closer, V For Vendetta completely fitted that particular bill, she asserts.
"When I received this script, I was so shocked by the idea that a big Hollywood action movie could actually have substance and be provocative, make people feel very strongly about things, whatever their reaction might be, I just thought `this is crazy, this is exactly the kind of entertainment I'm interested in making I've got to do it.'," she enthuses.
"It looks at the kind of choices that must be made in order to be a political person and how those choices affect an individual's private life.
"Coming from Israel, as I do, it was very interesting for me to consider the mind-set of someone who goes from being non-violent to being drawn towards using violence to express her political beliefs. That was something I'd been thinking about a lot, how someone might end up doing something like blowing up the Houses of Parliament."
V For Vendetta is in cinemas now.