America's controversial leader took to the stage on Tuesday (29Sep20) for the first of three debates with Biden, with one of the major moments in a chaotic affair coming when moderator Chris Wallace asked him to condemn white supremacist groups supporting him.
Trump responded by namechecking the Proud Boys white nationalist group, telling them to "stand back and stand by" - a slogan they have subsequently used on social media posts.
"Selma" director DuVernay tweeted, "For those who hadn't been listening for the past 4 years, Trump just told you that he ain't leaving and that he is a white supremacist. If that doesn't get every American who is not white into overdrive to toss his a** - we may actually deserve what happens next."
Ruffalo added, "I want to live in a country where my President is not afraid to call white supremacists and Nazis racists thugs and terrorists and then do everything he can to stop them."
Expressing his horror at the President's remarks, Chance the Rapper called the President an "openly racist White Supremacist" while Jewish actor Josh Gad also compared the groups' Trump was failing to condemn to the Nazis who "killed my family members."
Others who picked up on the remarks included Asian-American stars Mindy Kaling and Kumail Nanjiani, as well as the singer Jojo and Alyssa Milano - while others were angered by Trump's behaviour during the scrappy debate.
Kerry Washington tweeted, "That man is terrified that he isn't going to win. THAT is why he won't commit to conceding. He is already starting his immoral and illegal and unconstitutional tantrum."
Pink added, "Are you okay with this dips**t? Seriously? I'm so ashamed that we've lowered ourselves to even consider another term for this shameful loser. Even if you think it's still defendable behavior. Your children are watching."
Also providing a running commentary on the night's proceedings was Cardi B, who posted several videos of herself angrily shouting at Trump's responses to topics including on social justice, climate change, and allegations he avoided income tax.