Star power goes a long way.
Celebrities can often shed light, or make a big impact, on a cause or an issue in ways that even the best public relations campaign simply cannot.
During World War II, Hollywood stars promoted war bonds, rationing and Victory gardens. These days, they take to social media and television to get their points across on myriad issues affecting the world.
Five celebrities who made a difference this year:
: The pop superstar dipped her toe into celebrity activism in 2009 when she appeared at the National Equality March in Washington. But in 2010, Lady Gaga chose full-body immersion. She took on "Don't ask, Don't tell"
and encouraged her "Little Monster" fans to make a ruckus
by calling elected officials and asking them to repeal the law. For many Millennials, Lady Gaga's call to action was the first time they realized that they could even call a senator.
The fashion diva, who took heat from PETA for a costume made from meat, also lambasted Arizona's immigration law and took on the anti-gay Westboro Baptist Church
when the hate group protested her St. Louis concert. Her solution: Embrace them with love and peace.
How did she motivate her fans to action? Via Facebook
. Lady Gaga rules social media with more followers and fans than any politician, including President Barack Obama.
Expect the 25-year-old Lady Gaga to continue her fight for GLBT rights in 2011 as her third studio album will be called "Born This Way."
: Academy Award-winner Sean Penn went beyond the extra charitable mile in 2010. When Haiti suffered a devastating earthquake in January, Penn didn't just write a check to a relief agency. Instead, he started his own organization
and ventured to the ravaged country.
Penn became a camp manager for the International Organization of Migration at Petionville
, one of the most complex temporary camps in Haiti. The IOM is the United Nations agency responsible for camp management and coordination. He also traveled to Washington to testify at a Senate Foreign Relations Committee hearing on rebuilding Haiti.
In December, Penn, 50, even skipped out of a fancy Dubai film festival where he was to receive a lifetime achievement award to return to Haiti because of concerns regarding the safety of his staff. He received the "Hollywood Humanitarian Award" at the Hollywood Awards for his "selfless" efforts.
Penn continues to stress the importance of medical supplies and doctors as the country battles cholera. He's not going anywhere, he says. In fact, Penn has recently vowed to spend years in Haiti until the country is stable.
: Like first ladies before her, Michelle Obama has a cause -- childhood obesity. Sure, former Arkansas Gov. Mike Huckabee and Bill Clinton were pushing the issue long before Obama got on the scene, but she took the issue to a new level. She launched "Let's Move,"
a program to "raise a healthier generation of kids."
She has called obesity a "national security threat" and an epidemic. Last year, she created a White House garden
to show how easy it is to raise healthy food. She kicked off 2010 by speaking to the U.S. Conference of Mayors about the issue. This month, Obama celebrated a win when her husband signed into the law
the child nutrition bill for which she strongly lobbied. The first lady isn't above showing her hula-hooping skills or practicing with NFL teams to show kids how to exercise and get outside.
On her TLC reality television show, Palin said, "Where are the s'mores ingredients? This is in honor of Michelle Obama, who said the other day we should not have dessert." In fact, Obama said, "The problem is when things get out of balance, when dessert is practically a food group."
In turn, Huckabee, a former overweight diabetic who wrote a book about his weight battle, came to Obama's defense
. Don't expect Michelle Obama to back down on the issue. She plans to make the battle against childhood obesity her White House legacy.
In May, Palin appeared in a public service announcement for The Candie's Foundation, an offshoot of the clothing brand that promotes awareness of teen pregnancy. In 2009, she was named an ambassador for the foundation.
During her "DWTS" appearance, Palin filmed another PSA
promoting safe sex for the foundation with Jersey Shore star and fellow DWTS contestant, The Situation. He promotes condoms, Palin promotes abstinence.
In December, Keith Olbermann called Bristol Palin "the worst person in the world" because she preaches abstinence to teens even though she was an unwed teenager when she became a mom.
Palin pulled a Lady Gaga and took to her Facebook page to defend herself. She wrote: "In order to have credibility as a spokesperson, it sometimes takes a person who has made mistakes. Parents warn their children about the mistakes they made so they are not repeated. Former gang members travel to schools to educate teenagers about the risks of gang life."
Palin graduated out of her teens this year but is likely to continue her abstinence message into her 20s. That is unless she finds a new cause
Johnny Depp, Eddie Vedder, Natalie Maines and Patti Smith
: Collectively, these four kindred spirits came together in of all places, Little Rock, Ark., to shed light on the West Memphis Three
– Jason Baldwin, Damien Echols and Jessie Misskelley, Jr.
While teenagers, the three were charged with the murders of three 8-year-old boys, whose bodies were found in 1993 naked and bound in West Memphis, Ark. For the last 17 years, the three have been trying to get the Arkansas courts to retry the case. Echols sits on Arkansas Death Row. The other two men are serving life sentences.
Vedder and Depp have long been supporters of the West Memphis Three. Only this year, however, did Depp decide to become more vocal publicly about the case. Depp appeared on "48 Hours" to plead for a new trial and pulled his friend, punk goddess Patti Smith, into the project.
In August, Vedder, along with Arkansas Take Action
advocates, led the charge to organize a concert to shed light on the need for new hearings in the case. Depp, Maines and Smith appeared. Depp read poems written by Echols and also sang and played guitar. Maines, too, performed, and Smith closed the evening with her classics.
The celeb firepower may have just worked.