Ever since the first Harry Potter book was published all the way back in 1997, the world has been captivated by stories of The Boy Who Lived. As well as the seven main novels in the series, JK Rowling's creations also spawned a number of spin-off books, almost a dozen films, numerous real-life attractions, and, most impressively, an entire generation of kids who grew up wanting nothing more than to receive their Hogwarts acceptance letter.

The most recent addition to the franchise is the second Fantastic Beasts film, which is due to be released in theatres in November this year. As a final teaser ahead of the movie's premiere, a new trailer has been dropped - and fans were astounded to see that it confirmed a long-held theory about Voldemort's slithering companion, Nagini.

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Rumours about the snake (who, as fans of the franchise will know, was killed by Neville Longbottom in The Deathly Hallows) had been floating around for some time, but they started to become slightly more plausible when it was announced that Claudia Kim would be playing a "Maledictus" in the upcoming Fantastic Beasts movie.

For the uninitiated: a Maleditctus is, according to Pottermore, "a carrier of a blood curse which will ultimately destine them to transform permanently into a beast."

It had previously been theorised that Nagini was no ordinary snake, but was actually a Maledictus who had somehow become involved in Lord Voldemort's consort... and it turns out the theory was totally spot on.

In the new trailer, Kim's character is confirmed to be called Nagini, and has the ability to turn into a snake.

Here's the moment she revealed the exciting news on camera for the first time:

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Speaking about her role in the upcoming movie, Kim said: "It will be so interesting to see another side of Nagini. You’ve only seen her as a Horcrux. In this, she’s a wonderful and vulnerable woman who wants to live. She wants to stay a human being and I think that’s a wonderful contrast to the character."

She also hinted that there's a lot more to the snake than most us previously assumed.

"[Nagini] has powers that are yet to be explored," the actress said. "I can’t confirm she has powers like wizards have. And she doesn’t have a wand."

JK Rowling was also quick to react to the bombshell being dropped, and reminded people that a Maledictus is very different to an animagus (a person who can voluntarily turn into an animal and back into a human, such as Sirius Black).

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You can enjoy the latest trailer for yourself right here:

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As far as Harry Potter revelations go, this one is somewhere between 'Harry ends up with Ginny' and 'Snape kills Dumbledore' - meaning to say that it seemed likely, but it's still a huge deal now that it's finally been confirmed.

So get your wands and robes at the ready, folks, because you'll get to enjoy the full story very soon.

New 'Fantastic Beasts' trailer confirms an absolutely brilliant 'Harry Potter' fan theory about Nagini