Rowling wrote: "Yes, watching Piers Morgan being told to f--- off on live TV is *exactly* as satisfying as I'd always imagined."
Good Morning Britain presenter Morgan replied: "This is why I've never read a single word of Harry Potter."
The author picked up on the strangeness of his reply, commenting: "Because you had a premonition that one day the author would roar with laughter at seeing you called out for your bulls*** on live TV?"
Piers Morgan replied to this by saying she was "superior, dismissive and arrogant".
He wrote: "The superior, dismissive arrogance of rabid Remain/Clinton supporters like @jk_rowling is, of course, precisely why both campaigns lost."
She replied: "The fact-free, amoral, bigotry-apologism of celebrity toady Piers Morgan is, of course, why it's so delicious to see him told to f*** off."
And so it has continued. Morgan has since criticised Rowling in his Daily Mail column, saying her "sense of political and cultural self-importance is staggeringly overblown for a woman who writes about Hogwarts and Muggles."
Most recently, Morgan accidentally insulted his own writing after Rowling tweeted praise about herself she said she was anonymously sent by an admirer.
Seemingly incensed, Morgan wrote: "Priceless #humblebrag BS. Nobody plays the celebrity game more abusively or ruthlessly than you, Ms 'Intensely Private Billionaire'."
The praise was, of course, written by Morgan himself in a 2010 article for the Daily Mail.
Morgan has definitely come out the loser in this equation, becoming the victim of hundreds of trolls for picking a fight with her.
The Big Green Bookshop in London has bested them all, though, by tweeting Morgan every single line from the Harry Potter books one by one.
The co-owner, Simon Key, told Sky News: "I'm doing it because Piers clearly spends all day on Twitter staring at his timeline.
"He clearly needs a bit of a break from all the abuse, so as he mentioned that he hasn't read any JK Rowling, rather than having to tear himself away from Twitter to read it, I'd tweet him."
A version of this article originally appeared on telegraph.co.uk