When tennis player Serena Williams broke records during her match last weekend, people began talking about her on Twitter. But people did more than just discuss her athletic prowess - in fact, many of people's conversations merely glazed on her performance on the court, and instead focused on her muscular physique.

"Harry Potter" author J.K. Rowling is a huge fan of Williams, so she even shared a photo of them together before Williams' match. "I'm #TeamSerena today, because you don't meet many super-talented people nicer than she is. Go @serenawilliams!" she wrote.

So when a Twitter user decided to bash Williams for something completely unrelated to tennis, Rowling fumed and came to Williams' rescue in true Gryffindor fashion.

"@jk_rowling @hansmollman ironic then that main reason for her success is that she is built like a man," someone commented.

Rowling will not tolerate body shaming, so the outspoken author answered back by sharing a photo of Williams looking quite gorgeous in a skin-tight dress. "@diegtristan8 'she is built like a man'. Yeah, my husband looks just like this in a dress. You're an idiot," she tweeted.

Rowling has kept the fire burning for the "Harry Potter" franchise on her Twitter account, where she occasionally talks to fans and answers some of their questions. Just recently, she revealed that she regretted killing off the character of Fred Weasley the most.

There were several heartbreaking deaths in the "Harry Potter" series, most notably that of Dumbledore, Dobby the Free House Elf, Professor Severus Snape, Professor Remus Lupin, Nymphadora Tonks, and even Harry's loyal white owl Hedwig.

The author is currently busy working on her screenwriting debut for the "Harry Potter" spin-off movie "Fantastic Beasts and Where to Find Them." It will star Oscar winner Eddie Redmayne as the lead character Newt Scamander, a magical zoologist who travels far and wide in search of magical creatures.

His travels will even take him to New York City, and Rowling has revealed that there will actually be an American version of Hogwarts School of Witchcraft and Wizardry that will be introduced in the film.

She has not said what the name of the school will be though, but teased that the magic taught in the school will be heavily influenced by Native American history.

The movie will take place at least 70 years even before Harry, Ron, and Hermione step foot in Hogwarts and begin their education and adventures.