Lena Dunham likens Donald Trump to murderer Dylann Roof in scathing tweet

Lena Dunham tore into Donald Trump on Monday via Twitter, likening the "mentally ill" president to murderer Dylann Roof, who killed nine black churchgoers in 2015.

"Not only is he a racist, but he's a racist with untreated mental illness," Dunham wrote in response to several tweets by comedy writer Travon Free. "So under diff circumstances he's Dylann Roof."

Because the tweet was a response, most of her 5.6 million followers didn't see it -- but it elicited a mix of responses from those who did. While some agreed that Trump exhibits signs of mental illness, others took offense, accusing Dunham of being racist herself.

Although Dunham's comments have drawn some ire, other celebrities have perhaps more effectively called out the president, who last week referred to NFL players who kneel during the national anthem "sons of bitches."

"As a football fan, I am proud of the NFL players today. Nothing is more American than the right to peacefully protest," wrote Ellen DeGeneres.

John Legend went beyond Twitter: The artist penned an editorial for Slate, in which he wrote, "Protest is patriotic. Protest has played a critically important role in elevating the voices of the most vulnerable in our nation. Protest in America has been essential to ending war, to demanding equal rights, to ending unfair practices that keep citizens marginalized. If we quell protest in the name of patriotism, we are not patriots. We are tyrants."