Oprah Winfrey
It's no wonder she's the only person to appear on this list every year since it began. She's always moving forward, seeking, changing — like the great explorers who reset the horizon every time they sailed.
This month Oprah, 55, will broadcast her 4,270th hour of national television, a conversation with America that began in 1986. Her curiosity is undiminished. So is her passion for healing the bruised parts of the world and wielding truth against the bruisers.
This past year, for the first time, she publicly supported a presidential candidate, knowing full well the risk but unable to imagine any point to having power if you won't put it on the line for something you believe in.
She readied the 2010 launch of her new cable channel, powered up on radio, supervised her magazine and learned how to tweet. She flew tens of thousands of miles back and forth to the school in Africa whose 300 students remain the closest thing to her heart. She gets exhausted, she rallies, maybe because she knows what can happen when a brilliant little girl born into poverty gets it in her head that anything is possible.
How on earth can you summarize Oprah? If she were a destination, it would be the place where joy serves the world's great need.
And if she were your next-door neighbor, she'd pad over in pajamas, help you finish the bag of potato chips and laugh with you about the mistakes we all make on the road to learning something new.
It's said the average human has 100,000 heartbeats a day. Oprah may not have more of them than the rest of us, but each one is powered by purpose. And every year, somehow she reminds us anew of the song that plays in our best dreams.
Sawyer is a co-anchor of Good Morning America on ABC