J.K. Rowling's Flawless Response to Critic of Serena Williams

— -- "Harry Potter" creator and author J.K. Rowling has always been known to speak her mind.

So, when a Twitter user made fun of Wimbledon champ and 21-time grand slam winner Serena Williams over the weekend, Rowling took action.

It all started when Rowling tweeted "#SerenaSlam! I love her. What an athlete, what a role model, what a woman!" on Saturday.

She also tweeted, "I'm #TeamSerena today, because you don't meet many super-talented people nicer than she is. Go @serenawilliams!"

Someone then made fun of Williams' body, tweeting that she looks like a man, to which Rowling replied, "'she is built like a man'. Yeah, my husband looks just like this in a dress. You're an idiot."