Leonardo DiCaprio, Miley Cyrus and Brad Pitt

On this Earth Day, celebs far and wide will work tirelessly to save the world from environmental peril. Through public service announcements and the like, they will make us aware of carbon emissions, our polluted drinking water and how we're all going to die a horrible death at the hands of our disgruntled planet if we don't act NOW.

If there were a Celebrity Earth Day parade heading down Hollywood Boulevard, the Grand Marshall would almost certainly be Ed Begley Jr. He'd be waving from an itty bitty solar powered automobile, billed as an even smarter ride than the Smartcar. Begley was one of the first well-known actors to put his celeb voice behind the cause -- though he now has more Earth juice than star power.