2011 Heart of Green Awards

Winner: Matt Damon
Such a prolific philanthropist that he parodied himself on Entourage, Matt Damon has recently focused much of his energy on clean water. One group he co-founded, H2O Africa, has been confronting that continent's ongoing crisis. Another Damon project, Water.org, combines web 2.0 savvy, micro-loans and star power into a global, action-focused movement that is digging wells, safeguarding supplies and advocating for justice around the world, especially in distressed regions like Haiti.

Learn all about our 2011 greenest celebrity winner!

People's Choice: Leonardo DiCaprio
Long one of the most committed environmentalists in Hollywood, superstar actor Leonardo DiCaprio made waves in 2010, the Year of the Tiger, by teaming up with the World Wildlife Fund on the Save Tigers Now campaign. Working on financial, political and educational fronts, the project hopes to double the number of tigers in the wild, to 6,400, by 2022, the next time the iconic animal comes around the Chinese zodiac.

About the Nominees

Kevin Costner
While many celebs spoke out against the Gulf oil spill, Kevin Costner took direct action through an innovative, science-based startup he cofounded, Ocean Therapy Solutions. Costner had spent the last 15 years supporting research on centrifuge systems to more safely and effectively remove oil from water. Tests have been promising, and BP ordered 32 of the devices for the Gulf. Costner also testified before Congress, not just as a concerned actor, but as an expert in marine cleanups.

Michelle Obama
The First Lady has enjoyed high popularity since her husband's election, and it's not hard to see her appeal. Mrs. Obama has campaigned tirelessly for issues that cut across political lines, seeking smart solutions to rising obesity and poor nutrition. An avowed fan of natural and locally sourced foods, she has helped raise the profile of a movement. The Heart of Green Awards previously recognized her partner in the White House food gardens, Roger Doiron of Kitchen Gardens International.

Sigourney Weaver
A lifetime lover of the sea, actress Sigourney Weaver has become a spokesperson for marine conservation and for NRDC, particularly on the little-known yet critically important issue of ocean acidification. Weaver has also followed up her role in the smash hit Avatar by joining James Cameron in the fight for justice for the Earth's indigenous peoples, and to protect the last remaining untouched forests. The Planet Earth series Weaver narrates brings critical environmental issues into an unprecedented number of homes.

Jay Leno
Star comedian Jay Leno has become one of the most high-profile supporters of electric cars, and he recently accepted delivery of his new Chevy Volt, to considerable fanfare. Leno and his Big Dog Garage team have been greening up their operations for years, with wind and solar power, green cleaners and efficient tune-ups. They've been sharing their knowledge, including green motoring tips, on jaylenosgarage.com and new mobile apps.

- Brian Clark Howard