10 Greenest Celebrities

1. Robert Redford

The Sundance Kid is one of the most green-minded celebrities on this list, and spent about 30 years on the board of the Natural Resources Defense Council. Redford launched the Sundance Preserve, a nonprofit dedicated to protecting Utah's North Fork Canyon. He produced "The Green", a TV show for The Sundance Channel about environmental issues, such as solar energy and drilling in the arctic. He has campaigned on behalf of climate change and wilderness preservation issues and lobbied Congress for environmental legislation. Recently, he wrote op-eds to Obama against the Keystone XL pipeline.

2. Alicia Silverstone

Silverstone, who blogs about green living at The Kind Life, is a long-time environmentalist and vegan. Her book, the Kind Diet, describes why eating vegan is better for the environment and contains vegan recipes. She recently launched the Alicia Silverstone Collection of eco-friendly makeup and skincare products, which are animal friendly.

3. Ed Begley, Jr.

Begley starred in his own reality TV show, "Living with Ed", on the Planet Green Channel. The show chronicles his attempts to live his life with a smaller environmental impact and make his home more energy efficient - he even charges his toaster by peddling a stationary bike. He has his own brand of eco-friendly cleaning supplies called Begley's Best, and drives an electric car.

4. Edward Norton

Edward Norton, who starred in movies like Fight Club and American History X, runs BP's Solar Neighbor Program, which donates a solar PV system to a low income family every time a celebrity purchases one. Actors including Brad Pitt, Elton John, and Sting have participated in the program. He also serves on the Friends of the Highline in New York City, and regularly contributes to Earthjustice, the Grand Canyon Trust, and the Wilderness Society.

5. Daryl Hannah

Daryl Hannah, famous for her roles in Kill Bill, Splash and Blade Runner, has been arrested three times in environmental protest, including one opposing the Keystone XL pipeline. She once organized a 23-day tree sit to save Los Angeles' South Central Farm. She has an eco-video blog, DH Love Life, an online store for eco-friendly products, and has a solar powered home and biodiesel car.

6. Leonardo DiCaprio

This critically claimed actor launched the Leonardo DiCaprio Foundation in 1998, which is focused on sustainability and environmental causes. Through his organization, he teamed up with the World Wildlife Fund's Save the Tigers campaign, which hopes to double the number of tigers in the wild. He often flies commercially (rather than on a private jet) and drives a Prius.

7. Brad Pitt

While Brad Pitt may be best known for being named "Sexiest Man Alive" twice by People Magazine, he also has quite the eco-friendly resume. Pitt co-founded the Make It Right Foundation in 2007, which helped to build sustainable homes in the Lower Ninth Ward of New Orleans, which was destroyed during Hurricane Katrina. The homes, which are affordable at about $150,000, include low emitting paints and ENERGY STAR windows and appliances. He received an award from the U.S. Green Building Council for his efforts. Plus, he narrated a sustainable architecture design series on PBS called "e² design".

8. George Clooney

Clooney's role in award-winning "Syriana" inspired him to launch Oil Change, a campaign to end foreign oil dependence in the U.S. He owns two electric cars, including the Tango, which he was the first American to own.

9. Mark Ruffalo

Mark Ruffalo, due to receive the Entertainment Industry Environmental Leadership Award at this year's Global Green 15th Annual Millennium Awards, has passionately campaigned against hydrofracking in New York in Pennsylvania. He recently launched Water Defense, a foundation for clean water and clean energy solutions in the United States.

10. Adrian Grenier

Adrian Grenier, best known for his role as Vincent Chase in HBO's "Entourage", hosts Planet Green's TV show, "Alter Eco". He also started the website SHFT, which aims to make "video, design, art and culture" more sustainable. His Brooklyn home is powered by solar panels, and he drives a Prius.