Celebrities including Leonardo DiCaprio and Paul McCartney to Betty White and Miley Cyrus, have dedicated their free time to helping various animal causes around the world. The causes range from shelter adoptions and protecting wildlife to joining forces with PETA and the ASPCA. Here are some of the most vocal celebrity animal advocates.

Bob Barker Former television host Bob Barker is an animal enthusiast, strict vegetarian and life-long activist. Barker founded the DJ & T Foundation "to fund low cost spay/neuter clinics and voucher programs as a way to help relieve animal overpopulation." He dedicates much of his time to educating the community about the importance of animals rights, and he ended his "Price Is Right" episode with the phrase "Help control the pet population. Have your pets spayed and neutered." Host Drew Carey continues the mission even after Barker's retirement. Some other notable acts from Barker are his many donations to organizations striving to prevent animal cruelty. He gave millions of dollars to stop whaling ships in Japan. He also donated $1 million to Columbia University School of Law to support the study of animal rights. Due to his strong animal views, he stepped down from hosting the Miss USA pageant because real animal fur was awarded as prizes.

Howard and Beth Stern Long Island celebrities Howard and Beth Stern are avid animal lovers and activists, and spend time urging others to adopt pets. In December 2016, the couple partnered with North Shore Animal League America and a small group of friends to create a fund to enable the shelter to waive adoption fees for one weekend. Beth is a spokesperson for the North Shore Animal League and has appeared on TV and cable networks to spread awareness about shelter adoptions and animal cruelty.

Hayden Panettiere Back in 2007, an arrest warrant was reportedly issued in Japan for actress Hayden Panettiere with her involvement in a save the dolphins protest. Hayden joined a group of protesters who were trying to prevent Japanese fisherman from hunting dolphins in the area.

Paul McCartney Singer Paul McCartney is an animal rights activist and vegetarian since the 1970s. The singer narrated a PETA documentary, "Glass Walls," stating "if slaughterhouses had glass walls, everyone would be vegetarian." The documentary centered around the poor and at times inhumane treatment of farm animals. In 2012, McCartney formed a special connection with an elephant named Sunder he encountered on a trip to India. Sunder was given as a gift to an Indian temple in Kolhapur and was chained and repeatedly abused. When PETA learned of the mistreatment, Pamela Anderson and McCartney joined forces with the organization to help free Sunder from abuse. Years later, Sunder was released to a safe sanctuary with the help of these celebrities and the public's awareness.

Leonardo DiCaprio Actor Leonardo DiCaprio established the Leonardo DiCaprio Foundation with the mission of "protecting the Earth's last wild places and implementing solutions to build a more harmonious relationship between humanity and the natural world." DiCaprio has focused his humanitarian efforts on funding the protection of biodiversity, ocean and forest conservation and climate change.

Olivia Munn Actress Olivia Munn has worked with PETA numerous times to raise awareness for various issues. Munn participated in an interview with the organization to share her thoughts on the mistreatment of animals on fur farms. She also participated in a PETA PSA, warning people to boycott the circus because of the cruelty and physical punishment some of these animals face.

Ryan Gosling Actor Ryan Gosling has written numerous letters to organizations involving animal rights, including one he co-penned with actor Brad Pitt. The pair wrote to Craig Jelinek, CEO of Costco, urging the company to go completely cage-free and to stop buying eggs from suppliers who cage their chickens. Gosling has also written similar letters on behalf of PETA to KFC and McDonald's, asking the companies to consider more humane ways of handling chickens. He is also a proud dog parent and adopted his beloved mixed breed, George, from a Los Angeles shelter.

Ricky Gervais Comedian Ricky Gervais is a supporter of animal issues such as stopping China's Yulin Dog Meat Festival, where dogs are tortured and eaten, and he often speaks out about animal hunting.

Charlize Theron Actress Charlize Theron has worked with PETA on anti-fur campaigns.

Miley Cyrus Looking through Miley Cyrus' social media accounts you can see she has a love and respect for animals and is a proud vegan. The star often posts about the mistreatment of animals and exposes individuals who hunt for profit, food and to intentionally abuse animals.

Brad Pitt Actor Brad Pitt joined Ryan Gosling in writing a letter urging Costco's CEO, Craig Jelinek, to go completely cage-free and to stop buying eggs from suppliers who cage their chickens.

Ian Somerhalder Actor Ian Somerhalder created the Ian Somerhalder Foundation dedicated to promoting no kill-shelters and pet adoptions and his social feed is dedicated to animal rescue causes.

Hilary Swank Actress Hilary Swank created The Hilaroo Foundation to "bring youth, who have been given up on, and animals, who have been abandoned, together to help heal one another through rescue, rehabilitation, and responsibility training."

Gloria Steinem Noted feminist and writer Gloria Steinem, who has protested against cruel animal testing, joined PETA in 2016 in signing a petition against the San Fermín Running of the Bulls.

Jared Leto In 2015, Jared Leto was a WWF Global ambassador, spreading awareness for wildlife crime and poaching involving rare and endangered animals for profit. One issue in particular was the rhino poaching crisis in South Africa.

Pamela Anderson Actress Pamela Anderson is an avid supporter and honorary director of PETA. She created The Pamela Anderson Foundation to support "organizations and individuals that stand on the front lines in the protection of human, animal, and environmental rights." She has joined numerous charities and activism efforts to help protect animals, and has been awarded the Linda McCartney Award for animal protection and service. A native Canadian, Anderson works to combat the slaughtering of seals, and has acted as a diplomat and met with officials at the Russian Consulate in New York to promote Russia's seal-fur ban.

Pink In 2011, singer Pink teamed up with PETA to write a letter to former President Barack Obama to ensure his promise on U.S. Department of Agriculture cases against Ringling Bros. Circus and the mistreatment and abuse of the animals used in the shows.

Sarah McLachlan Singer and animal welfare activist Sarah McLachlan has appeared in television commercials for the ASPCA's campaign to end animal cruelty. The spots also feature her song "Angel," which has come to be associated with the cause.

Kristen Bell Actress Kristen Bell has a long history of supporting animal causes. She fostered animals and volunteered at local shelters in her home state of Michigan, and actively participates in charity events and fundraisers for the ASPCA.

Alicia Silverstone Actress and proud vegan Alicia Silverstone has been an animal advocate since she was a child and continues her mission to protect all types of animals. She has been involved in many causes including the Ark Trust Inc.'s Red Alert program, ensuring that animals in shelters aren't being accidentally killed before they can find forever homes. Silverstone has been a dedicated supporter of PETA, and in 1997 urged students in California schools not to dissect animals during class activities.

Betty White Betty White has a long history of working for animal welfare. She is a trustee of the Greater Los Angeles Zoo Association and has turned down roles in films when she believed the animals used would be mistreated. White turned down a role in the 1997 movie "As Good As It Gets" because of a scene that depicted a puppy being dropped down a laundry chute into a pile of clothing.

Martha Stewart Martha Stewart has spoken out against numerous animal rights issues including cruelty to farm animals and ending horse-drawn carriages.

Kellan Lutz The actor has worked with PETA to encourage people to adopt animals from shelters rather than buy from pet stores or breeders.

Kesha The Humane Society International named Kesha as its first global ambassador in 2011, and the singer also was awarded the 2013 Wyler Award from the organization. She has spread awareness for many animal causes involving animal protection including trophy hunting of endangered animals, seal slaughtering and abusing dogs.