Charlize Theron, Kristen Stewart and More Stars Attend Women’s Marches Around the World

What began as a simple Facebook invitation to protest the election of president Donald Trump turned into a global movement on Saturday, as millions of women (and men) across the world took to the streets in solidarity.

Their signature event was the Women’s March on Washington, D.C. — though a series of sister marches planned in all 50 states and six continents across the world were also scheduled. And among the political protesters lending their voices to the cause were a slew of famous faces.

Katy Perry was one of them. The vocal Hillary Clinton supporter shared a throwback photo of herself and her sister, Angela, before taking to the streets of D.C.. In the photos caption, Perry opened up about the cause and why her sister means so much to her.

“Marching with SO many sisters today but my heart is most proud to march with my blood sister, Angela, who has always been my guardian angel,” the 32-year-old singer wrote. “We should all be guardians for each other.”

Perry then explained why she was attending the march — explaining that while she may have felt misunderstood in the past, she now feels empowered.

“I march today because I am not afraid anymore and I hope I can be an example of fearlessness and resilience. I will not let anyone suppress me, silence me or clip my wings,” she wrote. “For a long time I misunderstood the true definition of being a feminist, but now that I know, I am empowered! I am indisputably a feminist.”

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“I am here today to break the cycle of suppression and inequality,” Perry added. “I stand with you all! #whyimarch @womensmarch.”

Two-time Oscar nominee Jessica Chastain gave fans a peek into some of the signs she and her friends made for Saturday’s march in D.C. “Who runs the world?” she wrote as she flexed her muscles alongside her pals and their signs — one reading “Girls just want to have fun-damental rights.”

The 39-year-old Zero Dark Thirty star will be bringing at least a dozen friends with her to the march, judging by the amount of “special guest” passes she showed off on social media.

Amber Tamblyn, 33, and Ellen Page, 29, both attended the march in D.C. Tamblyn wore a shirt that said “women are powerful and dangerous” — as she marched alongside “badasses” Callie Khouri (Oscar-winning screenwriter and creator of TV’s Nashville), television producer Katie Jacobs and president of the Planned Parenthood Federation of America, Cecile Richards.

It wasn’t just in Washington either. In London, English actress Sharon Horgan, of the Amazon hit Catastrophe, shared shots from the women’s march there. “Wonderful experience,” she wrote, adding that the marched from the U.S. embassy to Trafalgar Square.

Outlander star Caitriona Balfe shared shots of a women’s march in Edinburgh, Scotland — including a photo of a bearded man with a face full of makeup standing next to a woman holding a sign that read “Nasty girls grab back bigly!”

“Together we stand for equality, for inclusiveness, for respect,” the 37-year-old Irish actress wrote in the caption to one of her photos, of a large crowd holding signs like “Patriarchy is boring” and “Dump Trump.” She hashtagged the shot “#strongertogether #lovenothate.”

Chelsea Handler and Charlize Theron led a march in Park City, Utah, on Saturday — where many celebrities and entertainment industry types were gathered for the Sundance Film Festival. Kristen Stewart was also spotted at the march.

Helen Mirren and Whoppi Goldberg also joined marches in New York City.

Here are some of the other celebs who have shared their photos — including Eat Pray Love author Elizabeth Gilbert and Top Chef host Padma Lakshmi.

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The Women’s March on Washington began at 10 a.m. on Saturday — a day after Trump’s inauguration. Participants are expected to march down the intersection of Independence Avenue and 3rd Street.

“The Women’s March on Washington aims to send a message to all levels of government and the incoming Presidential administration, that we stand together in solidarity and expect elected leaders to act to protect the rights of women, their families and their communities,” officials said in the statement.

Organizations including Amnesty International, EMILY’s List, GLAAD, Girls Who Code, Muslim Women’s Alliance, Planned Parenthood, United We Dream and more partnered with the march’s national coordinating committee for the event.

America Ferrera also took on a leadership role in the event, serving as chairwoman of the Artist Table, “a diverse group of celebrities who will participate in and join in solidarity” with the march, event spokeswoman Alexandra Barnett told PEOPLE. (Ferrera also spoke at the event.)

“As artists, women, and most importantly dedicated Americans, it is critical that we stand together in solidarity for the protection, dignity and rights of our communities,” Ferrera said in the statement. “Immigrant rights, worker rights, reproductive rights, LGBTQIA rights, racial justice and environmental rights are not special interests, they affect us all and should be every American’s concern.”