“Your vendetta against me is causing collateral damage to innocent people,” the “Harry Potter” author wrote on social media.

J.K. Rowling is threatening legal action against a fan on social media.

The Harry Potter author quarreled with Wizarding News, a 22-year-old fan site, on X (formerly Twitter) on Wednesday.

Wizarding News had posted claims that Rowling has an estranged daughter and grandchild, which the author swiftly disputed. “This is untrue in all respects, as I suspect they already know,” she wrote in a post. “Lying about my kids is a new low, even by this website’s subterranean standards.”

“Your vendetta against me is causing collateral damage to innocent people,” she continued. “If legal action is the only way to protect them, I will take it.”

Reps for Rowling did not immediately respond to EW’s request for comment.

J.K. Rowling. Karwai Tang/WireImage

The fan account had posted, “Reminder that JK Rowling’s eldest daughter (the one with whom she was famously pregnant while writing Harry Potter) changed her last name to literally get away from Rowling, and moved to Portugal.” In another post, they said, “Did you know? JK Rowling is a grandmother. Have any of you ever seen her talk about grandchildren?”

In a follow-up post, Rowling explained why Wizarding News’ claims were false. “I’ve done everything I can to keep my children out of the public eye,” she wrote. “My eldest daughter doesn’t owe you or anyone else details of her private life. However, for the avoidance of doubt: 1. Contrary to your claims, we are very close and last talked an hour ago. We discussed your posts, which have angered and distressed her. 2. Contrary to your claims, she doesn’t live in Portugal. 3. Contrary to your claims, she has no children. 4. The young mother whose photograph and personal details you published is not my daughter and has no relation to me whatsoever.”

“You’ve published easily disproven and damaging falsehoods,” she continued. “Should we go to legal proceedings, you will need to show why, in spite of being told the truth, you neither retracted nor apologised. In the absence of any such retraction and apology, the next communication you receive will be from my lawyer.”

“I want a retraction and apology, or we go to lawyers,” Rowling wrote in another post.

Wizarding News later stated, “Deleted the post with photos and link to that Instagram hours ago, Jo. Glad you seem to be self-aware enough that you’re now publicly acknowledging the hate your bigoted rhetoric engenders.”

The account apologized to Rowling’s daughter for the mistake. “We are unreservedly sorry… to JK Rowling’s eldest daughter… for understandably mixing her up with a VERY coincidentally named person found in multiple published online articles & biographies identifying her as such, and extrapolating & sharing inaccurate details therefrom,” the account wrote. “Guess you could say we were following JKR’s example: ‘researching’ something & then immediately regurgitating it, [in our case unintentionally] spreading what some consider to be harmful falsehoods about others… which is what Rowling does to LGBTQ+ people daily,” they continued.

Rowling is notoriously anti-transgender rights and also recently made news for a spat with U.K. broadcaster India Willoughby, who reported the author to the authorities for alleged transphobia.