Call him quirky, but this guy is committed to the cause. And we'd be remiss if we neglected to mention him. Begley, Jr. has been rallying for the environment for years now. You'll never see him riding in anything but an electric car ... unless of course he's exercising his right to fight for the planet while pedaling around town on his trusty bike.

A true environmental hero, Ms. Panettiere does her part to protect all of Earth's creatures. And when a dolphin mission in Japan failed, Hayden Panettiere broke down in tears.

She isn't afraid to make a splash -- and she doesn't do things half way. Ms. Hannah has even been arrested for staging a 23-day sit in to save a garden in Los Angeles.

DiCaprio helped get Hollywood buzzing about the environmental issues. The actor co-produced, wrote, and narrated The 11th Hour, an eco-documentary that sheds light on the effects humans have on the environment. DiCaprio also drives a Toyota Prius.

Clooney lends a handsome face to a great cause. The rugged actor launched and supports Oil Change, a campaign to end America's dependence on oil. He also drives a Tango electronic car.

Norton has helped to launch the BP Solar Neighbors Program. The organization supplies low-income families with solar panels.

Blanchett converted her home in Australia into an eco-chic abode. She and her husband are co-directors of the Syndney Theatre Company, and they also plan on "greening" that venue.

She's got beauty, brains, and a conscience. Diaz has been photographed driving around the Hollywood Hills in a hot Toyota Prius.

Pitt has donated millions of dollars to help restore the damage in New Orleans from Hurricane Katrina. But not only is the actor and idol rebuilding the city – he’s rebuilding it green! All of the houses he’s helping to restore are eco-friendly and can even float on water in the event of a disaster.

Silverstone has been preaching the benefits of an organic and vegan lifestyle for years. The not-so-clueless star keeps a green solar-powered home. Even her kitchen table is recycled from the floor of an old bowling alley!