Warning: Spoilers for Fantastic Beasts and Where to Find Them

LOS ANGELES -- As fans suspected, it's official: Johnny Depp cameos in Fantastic Beasts and Where to Find Them as Gellert Grindelwald, aka "the second most dangerous Dark Wizard of All Time," according to sometimes credible (fictional) journalist Rita Skeeter.

The actor's 30-second appearance at the end of Fantastic Beasts is sure to provide gasps, and makes clear that Grindelwald will be the center of the planned five-film franchise.

For those that aren't major Potter-heads, remember: Grindelwald is one of the few characters in Fantastic Beasts that has been mentioned in the Potter-verse before.

While he's still fairly mysterious, we rounded up everything we know so far from the Harry Potter books about the dark wizard who appears set to be the main villain for this era of the franchise.

Grindelwald is first mentioned in J.K. Rowling's book series when Harry sees the dark wizard's name mentioned on a Chocolate Frog card featuring Dumbledore.

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The note on the frog read:

Considered by many the greatest wizard of modern times, Dumbledore is particularly famous for his defeat of the Dark wizard Grindelwald in 1945, for the discovery of the twelve uses of dragon’s blood, and his work on alchemy with his partner, Nicolas Flamel. Professor Dumbledore enjoys chamber music and ten-pin bowling

To put that into wizard history context, that means Grindelwald was around pre-Voldemort and was defeated at the same time World War II ended. The events in the first Fantastic Beasts film take place in 1926.

Rita Skeeter wrote about him in her book The Life and Lies of Albus Dumbledore, which played a critical role in the plot of Harry Potter and the Deathly Hallows because Harry learned a lot about Dumbledore from that text that he didn't already know.

Original image has been replaced. Credit: Mashable

Fans know that Skeeter isn't the most reliable of reporters (#neverforget Harry Potter and the Goblet of Fire) but she had a credible source on this one: Grindelwald's great aunt and magical historian Bathilda Bagshot (author of Hogwarts mandatory textbook A History of Magic).

She obtained the information in an unethical way, of course, via truth potion Veritaserum. That's how we know it to be true.

Crushing your crush

Skeeter wrote that Dumbledore and Grindelwald were actually friends and hung out in Godric's Hollow. They met when Dumbledore was 17, just after he left Hogwarts to take care of siblings Aberforth and Ariana after his mom died.

Grindelwald was indeed dark, but he apparently didn't exercise his "reign of terror" on the UK like Voldemort did. He focused more on getting the Deathly Hallows: Elder wand, Resurrection Stone and the Cloak of Invisibility.

Dumbledore was also interested in the Hallows because he wanted to see his parents again. Grindelwald's darkness apparently didn't rub off much on Dumbledore, though per Skeeter Dumbledore did have some anti-Muggle sentiments at some point.

The two plotted to lead a Wizarding revolution and create a world order led by wizards and witches to dominate muggles.

In 2007, at an event at Carnegie Hall, Rowling revealed Dumbledore was actually gay and in fact in love with Grindelwald.

"My truthful answer to you… I always thought of Dumbledore as gay," she said. "Dumbledore fell in love with Grindelwald, and that that added to his horror when Grindelwald showed himself to be what he was. To an extent, do we say it excused Dumbledore a little more because falling in love can blind us to an extent? But, he met someone as brilliant as he was, and rather like Bellatrix he was very drawn to this brilliant person, and horribly, terribly let down by him."

But Dumbledore's love for Grindelwald came to an abrupt end after the dark wizard cast the Cruciatus Curse on Aberforth after an argument with Dumbledore.

It turned into a three-way duel between Dumbledore, Aberforth and Grindelwald, during which Ariana ended up accidentally dying.

If you don't remember any of this, that's because the Deathly Hallows film barely touched on it. Aberforth was the one who helped Harry, Ron and Hermione get to Hogwarts through a portrait of Ariana (Neville came to get them) in the final film.

Goodbye Godric's Hallow

Grindelwald left Godric's Hallow and the U.K., and eventually stole the Elder Wand from Mykew Gregorovitch. He and his following in Europe then spent 19 years committing crimes -- including murder -- until Dumbledore found him in 1945.

That's when the two had their infamous duel, resulting in Grindelwald getting jailed and Dumbledore rising to worldwide acclaim.

How does Grindelwald's story end? Well, Voldemort came after him eventually when on a search for the Elder Wand. Grindelwald wouldn't tell him where it was so Voldemort -- of course -- killed him.

Time will tell if the events in the next Fantastic Beasts films will directly follow this timeline or if J.K. Rowling has a few more tricks up her sleeve.

One thing is for sure, though: The search is on for an actor to play Young Dumbledore.