Looks like Margot Robbie took her "Harry Potter" obsession pretty seriously during her teenage years.

The 25-year-old Australian actress made an appearance on "Jimmy Kimmel Live!" on Tuesday, when she revealed herself to be a "massive 'Harry Potter' nerd." The topic came up while discussing her latest film, "The Legend of Tarzan," since it was directed by David Yates, who also directed four of the "Harry Potter" films. Yates is also directing the highly anticipated adaptation of author J.K. Rowling's "Fantastic Beasts and Where to Find Them."

And if you thought the gorgeous blonde couldn't possibly have any awkward childhood photos, think again. Kimmel ended up surprising Robbie with a hilarious throwback snap of herself in bed reading "Harry Potter" in a turtleneck and glasses, holding a cup of tea.

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"Literally, the most embarrassing photo of my whole life," Robbie laughed, explaining that it was taken on her 13th birthday. "I'm clearly really enjoying myself reading 'Harry Potter.' I have braces, which I had for two years. I was really into slicking my hair back, God knows why. And I'm wearing glasses, which I didn't actually need."

Robbie admits she lied to get prescription glasses so she could look like "Harry Potter," when in reality, her vision is 20/20.

"They're not even cool ones, they're like, ugly glasses," Robbie joked. "I went to the optometrist and was like, 'No, I can't see that. Oh, my eyes hurt!'"

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ET chatted with both Robbie and her "Tarzan" co-star, Alexander Skarsgard, earlier this month, when they dished on filming animalistic love scenes for the film.

"I think it's difficult with someone like Margot to not have great chemistry, because she's the most lovely, warm personality," Skarsgard gushed. "It didn't take long. We had so much fun together."