The young star who plays the invincible cheerleader, Claire Bennett on Heroes became an official spokesperson for Declare Yourself, a national non-partisan and non-profit campaign which aims to involve 18-year-olds in the United States to register and vote in the upcoming 2008 elections.

The campaign, which was founded by television producer and philanthropist Norman Lear, was first introduced as the Declaration of Independence Road Trip during the 2004 U.S. presidential elections. The campaign's PSAs, which were released last year, was directed by David LaChapelle and were presented as commercials for different products, all ending with an image conveying silence. Then the phrase, "Only You Can Silence Yourself" appear, followed by a voice whispering, "Register to vote now."

2004 and 2006's national elections were supported by more than 1.2 million voters who registered through Declare Yourself's online registering system. Today, Declare Yourself has collaborated with Yahoo!, MySpace, YouTube, Google, Evite, Good Search, Clear Channel, Comedy Central and American Eagle Outfitters to further reach out to the youth.

"Declare Yourself makes the process so easy to do," Hayden Panettiere said in a statement. "I can't think of a better way to make a difference in today's society than by voting to make sure that my voice is heard."

On the eve of her 18th birthday, Hayden Panettiere appeared on David Letterman's late night talk show as a guest. While there, she joked about legally becoming an adult in the U.S.

"I don't think much changes when you're 18 ? maybe the way people treat you," said the Heroes star to David Letterman. "But I think the only things I can do is buy cigarettes, porn and, if I get in trouble with the law, I'm kind of screwed."