Jodie Foster and Michael J Fox have led an anti-Donald Trump protest two days before the Oscars in Los Angeles.
The United Voices rally was staged by Hollywood's United Talent Agency instead of its usual pre-Oscars party.
Foster, a double Oscar winner, said she rarely spoke out in public but that it was now "time to show up".
Back to the Future star Fox told the crowd "we are the lucky ones" and that he wanted to "share a bit of that luck" with refugees who want to enter the US.
"I believe that when so much good has been done unto you it's natural to feel a sense of civic or even global responsibility," he told the Beverly Hills rally.
"I consider myself an optimist and that can be a tall order at times for me personally, and more as I see a growing intolerance and lack of compassion and empathy in the world around us.
"But one's dignity may be assaulted, it may be vandalised, it may be cruelly mocked, but it can never be taken away unless it's surrendered."
The Canadian-born star, who became a US citizen two decades ago, showed only relatively small signs of the Parkinson's Disease he has lived with since 1991.
He added that he believed "in the power of the arts to change not just our hearts but the world".
Foster, meanwhile, who has won Oscars for The Silence of the Lambs and The Accused, said the rally was "exactly the way to celebrate our industry, to celebrate all of you, to celebrate artistic expression and our commitment to humanities on screen and off".
She did not air her views in public often, she told the crowd during her impassioned speech. "I'm not somebody who's very comfortable using my public face for activism.
"And so in my life I've found the small ways, much like most of you, to serve and to show up and to give somebody a lift at the bottom of the hill when they're going to the top.
"But this year is a very different year and it's time to show up. It's a singular time in history. It's time to engage."
She added: "When we get to celebrate excellence in film like we're doing today, like we're doing this week, we can't forget that this industry is in the business of humanism.
"It's that compassion that makes us strong. It's doing the right thing that makes us just."
The rally comes ahead of an Academy Awards ceremony that is likely to be highly politically charged.
Mr Trump has previously been dismissive of celebrity protests and of stars who have criticised him, such as Meryl Streep.
The rally was also shown a video message from Oscar-nominated Iranian film director Asghar Farhadi, who has said he is staying away from Sunday's ceremony following Mr Trump's attempt to ban travel from Iran and six other mainly Muslim countries.
Also on Friday, all the nominees for best foreign language film - including Farhadi - issued a joint statement denouncing the current "climate of fanaticism and nationalism".
They said: "Regardless of who wins the Academy Award for best foreign language film on Sunday, we refuse to think in terms of borders.
"We believe there is no best country, best gender, best religion or best colour. We want this award to stand as a symbol of the unity between nations and the freedom of the arts."