Brazilian model Gisele Bundchen, along with her husband, US football star Tom Brady, have adopted a plant-based diet.
"In the beginning he was like, it was a little, you know, different for him," Gisele has said of her hubby's transition.
"But now he loves it, and he wouldn't have it any other way, because he feels better."
Emily Deschanel is an animal rights activist and says farm animals are her main concern.
"Going vegetarian or vegan is certainly a way to lessen your footprint on the Earth."
An avid animal lover, Alicia Silverstone became vegetarian at 12 and vegan at 18. But she talked about how veganism transformed her health.
"Once I went vegan, I lost the weight I wanted to lose, my nails were stronger, and my skin was glowing."
Casey Affleck is a keen animal rights campaigner and vegan whose support stems from a childhood pet.
"The first dog I had was owned by an abusive couple."
Anne Hathaway showed her commitment to cruelty-free ethics when she stepped out in a custom-made vegan version of Tom Ford's gladiator dominatrix boots.
Joaquin Phoenix was raised as a vegan and is an ambassador for PETA.
Last year he starred in a PETA commercial urging people to relate to the suffering we cause fish when they're taken from the water and die by suffocation in which Phoenix simulated drowning.
Jay-Z and Beyoncé
Jay-Z and Beyoncé jumped on the 22-day vegan challenge bandwagon, saying it was a "spiritual and physical cleanse".
They got into it, posting plenty of photos of their vegan meals on Instagram, but didn't stick with it.
After completing the 22-day challenge Jennifer Lopez stayed vegan, although she has re-introduced some fish to her diet so technically she's a pescatarian.
Lopez says, "Butter is the one thing I miss! Butter makes everything taste better."
Tobey Maguire became a vegetarian in 1992 and vegan in 2009.
He has said giving up meat was easy: "I've never had any desire to eat meat. In fact, when I was a kid I would have a really difficult time eating meat at all."
Actress and director Olivia Wilde says: "[Being vegan] is not always easy and accessible. But it's a way of life and makes me as a person feel really good and physically look better."
She briefly abandoned it during her pregnancy but went back to veganism.
Bryan Adams campaigns for Greenpeace and PETA and says: "I've made a conscious decision not to be part of the cycle of killing animals because I couldn't see the point of crusading for Greenpeace and then eating a fish."
Czech model Petra Nemcova stopped eating meat and animal products in 2007 after learning about the planet's rapidly depleting fish stocks.
Ellen DeGeneres went vegan in 2008 and tries to spread the joy of cooking and eating plant-based food.
She has admitted to eating eggs, saying "We have neighbours who have chickens, and we get our eggs from those chickens because they're happy."
Portia de Rossi
Ellen's wife and actress Portia de Rossi is also committed to a cruelty-free lifestyle.
"It feels like such a compassionate choice. We are such animal lovers, why stop short of cows and chickens? It didn't make any sense."
Actor-turned-rock-star Jared Leto and the rest of his band mates are all strict vegans.
"Well, there was a time when we used to sacrifice goats, but then we all became vegans, so we've been sacrificing tofu before the shows!"
Glee star Lea Michele turned vegan for the health benefits as well as animal rights reasons.
"It's about being good to your body and the planet."
Brad Pitt is said to have been a vegan for years, although Angelina Jolie isn't any longer, saying.
"I was a vegan for a long time, and it nearly killed me. I found I was not getting enough nutrition."
Woody Harrelson is a long-time vegan and advocated for a raw food diet and medicinal herbs.
The actor also uses only solar power at his house, making him a bona fide eco-celeb.
Legendary dance musician Moby has been consistently vocal about his vegan beliefs, even naming his 1996 album Animal Rights and opening a vegan café called TeaNY in New York.
Radiohead's Thom Yorke is known as an environmental and animal rights activist but he admits he stopped eating meat for a different reason.
"I started going out with this girl and I wanted to impress her so I pretended I'd been vegetarian all along..."
Bill Clinton was named PETA's Person of 2010 after he began promoting the benefits of vegan eating.
He changed his own habits for health reasons and thanks to the plant-based diet, has lost a lot of weight.