The 2008 TIME 100

Oprah is a wonderful friend and an incredible force. Her friendship and support have meant so much to Barack and me.

As Barack often says about his own life, Oprah's story is one that truly could happen only in America. After the struggles she endured as a young girl, she became a popular talk-show host with a national following. But she didn't stop there. Using her platform to serve as a global role model, she challenges us to make the world as it is the world as it should be. And she is always the first to show us how it can be done.

In the past few months, I've had the privilege of watching Oprah inspire thousands of Americans to participate in our democracy. She has also reached out to thousands more who might not have known there was a seat for them at the table at all—people who desperately need a voice.

Over the past 20 years, Oprah, 54, has developed and nurtured a relationship with her viewers and readers built on the recognition that there is more that unites us than divides us—that our shared experiences in work, life and love, in family and community, in our hopes and dreams, know no barriers; that regardless of race, gender, socioeconomic status or hometown, we are our brothers' keepers, our sisters' keepers.

For this impact on all of us, I am honored to honor Oprah, the only person to make this list every year since it began.

Obama, a lawyer, is the wife of presidential candidate Barack Obama