Happy Earth Day! Here Are 15 Environmentally-Conscious Celebs

Panettiere is passionate about protecting dolphins from being hunted, both to place them in captivity or butcher them for meat. She's part of the 2009 documentary The Cove, where she and some surfers paddle out to the Japanese cove where dolphins are being hunted, and everyone is overcome with emotion.

The sexy vampire drama is a green set, apparently: Kristin Bauer and Stephen Moyer separate their recycling, while Alexander Skarsgård advocates for the whales. Also on the animal front, Rutina Wesley and others helped out at an animal rescue event called (no joke) "True Blood Hounds" last year.

These celebs are part of UNICEF's Celebrity Tap Project, which sells celebs' tap water to fans. Every dollar ensures 40 days of clean water to a child in need; the minimum donation is $5. Check out Gomez's video here.

DiCaprio basically wins at celebrity environmentalism: He flies on commercial flights and drives a hybrid car; his documentary 11th Hour looked at the effects of global warming; and he's working to save the tigers. He even has a foundation named after him!

When the BP oil spill catastrophe occurred a year ago, Costner unexpetedly stepped forward with a machine he had developed, which he said could extract 97% of the oil from the polluted waters. Sure, it brought on some Waterworld jokes, but it was still heartening to see a public figure step foward while BP was equivocating.

As part of her work for Charity Water, Bell visited countries in Africa: Uganda to build wells, and Kenya, where she got smooched by a giraffe. She also encouraged her Twitter followers to conserve water for 30 Days of H2O in February.

The actress is teaming up with Kiehl's to design custom labels for the company's new Açaí Product Damage-Protecting Toning Mist--available today. Proceeds go to the Rainforest Alliance.

The famous couple has more than a few years on their environmentally-conscious contemporaries: In 1989 they set up the Rainforest Foundation to help the communities threatened by deforestation. However, some see Styler as a hypocrite; she was recently criticized for flying her entire entourage by private jet from NYC to Washington for a party.

Portman's been part of environmental causes all her life, it seems: She joined a singing and dancing group called World Patrol Kids; she christened a gorilla; she discussed microfinance at the Live 8 concert; and she launched a line of vegan shoes.