It's relatively rare these days to find a celebrity who hasn't lent their voice to a good cause, whether that's for personal passion projects or a spot of good publicity.
However, there are some stars so entrenched in activism that their work in this area has become almost as famous as the career that made them a household name in the first place.
As a number of A-listers spoke out and protested against anti-Asian hate crimes in the US this week, we round up some of the most famous celebrity activists alive today, who speak out on everything from women's rights to environmental causes and matters of social justice.
This list is in alphabetical order.
The American actress and singer might only be 22, but she's already been making waves for years. In 2015 and 2016, the The Hate U Give star was named one of Time's Most Influential Teens, as well as the magazine's Next Generation Leaders in 2018.
Her activism dates back years, to when she produced a Tumblr video called Don't Cash Crop My Cornrows as a school project, sparking conversation about cultural appropriation, and she's continued to use her social media platforms to advocate human rights and feminist issues.
In 2019, she was given the Visibility Award, by Human Rights Campaign, a civil rights organisation dedicated to achieving LGBTQ+ equality.
The Ugly Betty star and Ted speaker was born in California to Honduran parents and has been fighting the good fight for Latino rights.
Along with nine other Latina leaders, actresses and activists, Ferrera launched She Se Puede in 2020, a digital platform and community dedicated to empowering Latin American citizens during election year.
She's also an author, having released a bestselling book called American Like Me: Reflections on Life Between Cultures, a collection of first-person accounts of growing up between cultures in America, and co-founder of Harness, a community of artists and grass roots leaders who provide education and engagement opportunities to social justice organisations and activists.
Angelina Jolie is as much known as a humanitarian as she is Hollywood royalty. She's actively involved in a number of causes, including conservation, education and women's rights, but she's perhaps best known for her role as a Special Envoy for the UN High Commissioner for Refugees, a title she was given in 2012, after more than 10 years of being a Goodwill Ambassador for the agency.
In this role, the Tomb Raider star focuses on major crises that result in mass population displacements, representing the UNHCR at a diplomatic level and helping find solutions for people forced to flee their homes.
You can't very well talk about celebrity activists without bringing up one of the most famous philanthropists of all time (next to Bob Geldof), although the Irish musician has not been without his critics.
The U2 frontman was one of those Geldof enlisted to sing on the Band Aid track Do They Know It's Christmas? in 1984 (which has also since received plenty of criticism for its portrayal of Africans, among other things), and has performed at a number of politically motivated concerts throughout his four-decade music career.
He's known to have championed causes as wide-ranging as debt relief to Aids awareness, and worked with non-profits such as Amnesty International and Greenpeace.
Bono, whose real name is Paul David Hewson, has always been particularly active in matters relating to Africa, and has founded a number of non-profit organisations, including One Campaign, an advocacy and campaigning group that fights extreme poverty and preventable disease across the world.
It's possible that, to this day, Emma Watson is best-known for two things: for taking on the role of Hermione Granger in the Harry Potter film series, and for her outspokenness on women's rights.
The British actress was appointed a UN Women Goodwill Ambassador in 2014 and dedicates time to empowering young women, serving as an advocate on the HeForShe campaign, which promotes gender equality.
George Clooney is another famous philanthropist who is active in a number of causes, alongside his wife, Amal, a Lebanese-born British human rights lawyer. Together they work on the Clooney Foundation for Justice, which advocates justice through accountability for human rights abuses around the world.
A number of causes close to the Syriana actor's heart, aside from general human rights abuses, include gun control, the refugee crisis and LGBTQ+ rights.
Clooney is a former UN Messenger for Peace, however he stepped down saying he no longer had time for the role.
The former Miss India is one of Bollywood's most famous activists. She runs The Col Shamsher Singh Foundation, named after the commander of the Sikh Regimental Centre of the Indian Army, which focuses on a variety of causes, including gender equality, education and disaster management.
Panag has also had a career in politics, and was the Aam Aadmi Party candidate from Chandigarh for the 2014 Indian general election, in which she came third.
The Grace and Frankie actress is not only a veteran in Hollywood, but also has decades of protesting and activism under her stylish belt. Even in her eighties, she's as committed a rebel as she ever was, speaking for a range of causes, from women's rights to Black Lives Matter.
She was arrested five times in 2019 for her Fire Drill Friday protests, weekly demonstrations on Capitol Hill to demand that action by political leaders be taken to address the climate emergency. She even continued these virtually amid the pandemic.
She's known for many things, but in recent years Kim Kardashian has become renowned in the world of criminal justice reform, as she trains to become a lawyer.
The reality TV star speaks for those wrongly jailed, and became particularly passionate about the cause after successfully petitioning former US president Donald Trump for clemency in the case of Alice Marie Johnson, who had been sentenced to life in prison for a nonviolent drug-related crime.
A feature-length documentary, Kim Kardashian West: The Justice Project, reveals more on the case and others close to Kardashian's heart.
The American singer-songwriter and actress, born Stefani Germanotta, may be known for her wild outfits and out-there antics, but she's got a much more humble and soft side to her.
Her brand of activism and charitable giving is mostly directed at mental health awareness and LGBTQ+ rights. That's why, in 2012, she founded with her mother the Born This Way Foundation, a non-profit that supports the mental health of young people and works with them to "create a kinder and braver world".
She's also been a supporter of a wide range of other movements, from Artists Against Fracking to Black Lives Matter and the relief efforts from the 2011 Tohoku earthquake and tsunami in Japan.
Easily one of the most famous environmentalists in Hollywood, Leonardo DiCaprio has been vocal for our planet for decades. In 1998, the Titanic star founded the Leonardo DiCaprio Foundation, with a mission to protect the world's last wild places. This includes programmes on wildlands and ocean conservation, climate change, indigenous rights and coming up with innovative solutions to dire global problems.
DiCaprio is also a UN Messenger of Peace of Climate Change and sits on the boards of several environmental organisations, including the World Wildlife Fund, National Geographic Society's Pristine Seas and the International Fund for Animal Welfare.
He also produced the 2016 documentary Before the Flood, in which he meets scientists, activists and world leaders to discuss the dangers of climate change and possible solutions.
Most people will know Mark Ruffalo is a very good actor, but it's possible not everyone knows the Now You See Me star is also a staunch environmental activist.
He's particularly anti-fracking and also founded the non-profit organisation Water Defence, which aims to advocate safe, clean water practices by performing testing in contaminated areas, as well as raising awareness of information and resources to combat water pollution. The group has also worked to ban hydraulic fracturing (fracking), used to extract oil and gas from the earth, in New York and Colorado.
Michael J Fox
The Canadian-American may have retired as an actor, but his activist work continues with The Michael J Fox Foundation For Parkinson's Research.
The Hollywood actor, who is well-known for the Back to the Future films, was diagnosed with Parkinson's disease in 1991, when he was only 29.
In 2000, he founded his organisation, which today is the world's largest non-profit funder of Parkinson's drug development.
If you're a fan of environmental and wildlife documentaries, you'll know Morgan Freeman's voice well, as he's lent his smooth vocal cords to titles such as March of the Penguins, Born to be Wild and Island of Lemurs: Madagascar.
The Seven actor also helped form the Grenada Relief Fund in 2004, to aid people affected by Hurricane Ivan on the island of Grenada, and turned his ranch into a bee sanctuary after learning about the decline of honeybees.
He's vocal on racial issues in America, too.
You might remember Natalie Portman wearing a cape embroidered with the names of snubbed female directors at the 92nd Academy Awards in 2020, but gender equality is not the only thing the Black Swan actress is vocal about.
Portman is a long-time vegetarian-turned-vegan and supporter of animal rights, having narrated a documentary called Eating Animals.
She is also involved in anti-poverty campaigns and is an ambassador for Foundation for International Community Assistance (Finca). The Israeli-born star is also a member of the OneVoice Movement, a global initiative that supports grass roots activists around the world helping to find solutions for issues in Israel and Palestine.
Rahul Bose, a notable Indian actor, director and screenwriter, is possibly one of the most prolific activists from the country's entertainment industry.
In 2007, he launched The Foundation, a non-governmental organisation dedicated to removing discrimination from all walks of life.
The former rugby player was Oxfam's first global ambassador from the eastern hemisphere, and launched the charity's India initiative on climate change in 2009. He was also heavily involved in the grass roots initiative Planet Alert, and was the first Indian to deliver lectures for Climate Action Network to the South Asian-Canadian community on the global politics of climate change.
He has worked with many famous NGOs over the years, delivered many talks and even won awards, all in the name of social and environmental justice.
A woman of many talents, Reese Witherspoon is known for her acting and business prowess, as well as her writing skills and ability to spot a great book.
She's also spent many years fighting for greater representation in Hollywood of women, people of colour, LGBTQ people and those with disabilities.
This is one of the reasons why she founded her media brand Hello Sunshine, as it "puts women at the centre of every story we create, celebrate and discover".
American actress and director Regina King was the first celebrity to commit to the 4% Challenge by non-profit Time's Up, which urged industry leaders to take a pledge to work with a female director.
She also wrote in a USA Today op-ed in 2019 that she made a commitment to, within two years, have women make up 50 per cent of the crew for projects she produces. While the pandemic may have slowed this goal, King continues to speak out on gender issues.
The If Beale Street Could Talk star is also passionate about helping at-risk children, and is a supporter of the "I Have a Dream" Foundation.
Riz Ahmed is a great actor. So great, in fact, he is the first Muslim nominee in the Best Actor category at the Oscars. But the English star is also an activist, known for raising funds for Syrian refugee children and advocating more representation at the UK Parliament's House of Commons, according to Time magazine, which named him one of the world's 100 most influential people in 2017.
The Sound of Metal star has also been involved in raising awareness of and funds for Rohingya refugees.
While perhaps not an activist in the same sense as others on this list, the Charmed actress deserves a special mention after she was among the first to go public with rape accusations against Harvey Weinstein. She has since been named as one of The Silence Breakers, Time magazine's Person of the Year in 2017, for her prominent role in sparking the #MeToo movement.
The American actress has written a memoir, Brave, about her sexual assault and her childhood living as part of the controversial group Children of God.
You might recognise Shailene Woodley, an American actress and film producer, from the film Divergent or series Big Little Lies, but then again you might remember her face from the protests she's been part of, too. In particular, she made headlines when she was arrested after protesting the Dakota Access Pipeline in 2016.
The award-winning activist is very into all matters relating to the health of our planet, from joining researchers on a Greenpeace sea expedition right down to making her own toothpaste.
In 2010, she co-founded with her mother the non-profit organisation All It Takes, a youth leadership programme to educate young people on compassion and responsibility for the environment.
A couple of years ago, Woodley also became an Ocean Ambassador for Greenpeace and embarked on an expedition to study the impact of plastics and microplastics on marine life.
The Indian actor, producer and model's social work has reached a peak during the Covid-19 pandemic, as he arranged transportation for migrants stuck in Indian cities to go back to their hometowns and villages.
For this, he was given the SDG Special Humanitarian Action Award by the United Nations Development Programme, and on Saturday, was honoured by SpiceJet airline with a special livery on its planes with an image of the Arundhati star and a line that read, "A salute to the saviour Sonu Sood".
You know you're a successful activist when even Michelle Obama takes notice. That's what happened to American model and actress Yara Shahidi, as the former first lady went on to write her a letter of recommendation to Harvard University.
So what does she advocate? A number of things, including poverty, voting, women's rights and even actor Jussie Smollett.
In 2018, the black-ish and grown.ish star launched Eighteen x 18, an initiative that urged young Americans to vote in that year's mid-term elections.
Zahra Lari made history not just by becoming the first figure skater from the UAE to compete internationally, but also for convincing the International Skating Union to change their rules to allow Muslim skaters to cover their hair.
The Emirati sports star then became the first professional figure skater to compete internationally wearing a headscarf, and went on to appear in a world-famous ad campaign for the Nike Pro hijab.
Lari has been inspiring Muslim girls all over the world through her bravery ever since.