But one of Trump's latest critics, "Harry Potter" author J.K. Rowling , may have some of the harshest words yet for the Republican front-runner's controversial policy proposal.

How horrible. Voldemort was nowhere near as bad. https://t.co/hFO0XmOpPH — J.K. Rowling (@jk_rowling) December 8, 2015

"How horrible," tweeted Rowling, along with a BBC report on Trump's call to ban Muslims. "Voldemort was nowhere near as bad," she added.

And fans of the fantasy novels know just how serious a comparison to the "Dark Lord" is.