Through his William J. Clinton Foundation, former US President Bill Clinton has become a vital and innovative force for world change. He works in four critical areas: health, economic empowerment, citizen service, and reconciliation.

Indie newcomer Sophie Hunger's haunting vocals -- at once fragile and soulful -- carried her wistful, blues-dappled acoustic folk from intimate cafe appearances to extraordinary word-of-mouth success and cross-Europe tours.

Scott Kim designs puzzles in the spirit of MC Escher's art and Tetris -- visually stimulating, thought provoking and suffused with broad appeal.

Kathy Mendias is a certified childbirth and lactation educator and doula with a passion to educate and support expecting couples and promote emotional health through embracing life's tears.

Scott McCloud is author of Understanding Comics, a comic book about comics. He's an evangelist for comics as a valid literary form (as more than pulp and kids' stuff) and his admiring fans include a laundry list of superstar cartoonists.

Randall Munroe sketches elegant and illuminating explanations of the weird science and math questions that keep geeks awake at night.

Christen Reighter writes and performs as a poet and essayist, focusing primarily on social justice issues.

Kashmir Hill writes about privacy and technology.

In 2021, Safi Rauf was taken captive by the Taliban while working to provide resources and assistance to Afghans in need. He was released after more than 100 days in jail and remains committed to aid work in Afghanistan and around the world.

Shankar Vedantam is a science writer obsessed with understanding why humans behave the way we do -- and what it says about us.

Manish Bhardwaj believes that moral clarity should guide how we use science, engineering and technology to create a more just world.

Latif Nasser is the director of research at Radiolab, where he has reported on such disparate topics as culture-bound illnesses, snowflake photography, sinking islands and 16th-century automata.

Lost jobs, wayward lovers, wars and famine -- come to think of it, just about any of life's curveballs -- there's an aphorism for it, and James Geary's got it.

KC Davis offers a compassionate and practical approach to self and home care for those dealing with mental health, physical illness and hard seasons of life

Sergey Brin is half of the team that founded Google.

Writer, comic and mental health activist Kevin Breel speaks up about depression.

A record-setting triathlete, Minda Dentler is a polio survivor committed to inspiring people to move beyond their fear of failure and achieve their goals.

BCG’s Lana Mazahreh wants individuals, companies and countries to take action against the fast-growing water crisis.

Corey Hajim curates world-changing ideas from the brightest and boldest minds in business.

Nandan Nilekani is the author of "Imagining India," a radical re-thinking of one of the world’s great economies. The co-founder of Infosys, he helped move India into the age of IT.

Roberto D'Angelo and Francesca Fedeli created the social enterprise FightTheStroke.org to open up a dialogue about the devastating effects of strokes at a young age. This issue is important to them for a simple reason: because they've been through it themselves with their son Mario.

Georgette Mulheir is a pioneer for the movement to end child abuse in the form of orphanages.

His production credits range from Amy Winehouse to Paul McCartney -- ace DJ, musician and producer Mark Ronson has lived recent music history from the inside out.

Philip K. Howard is the founder of Common Good, a drive to overhaul the US legal system. His new book is "Try Common Sense."

Sanjit “Bunker” Roy is the founder of Barefoot College, which helps rural communities becomes self-sufficient.

Michael E. Porter wrote the books on modern competitive strategy for business. Now he is thinking deeply about the intersection between society and corporate interests.

In 1994, Esta Soler was among the key advocates for a US law to combat the devastating effects of violence against women. Today, her mission is global.

Adam Driver is working to bridge the cultural gap between the United States Armed Forces and the performing arts communities by bringing the best modern American theater to the military.

Aspiring Olympic skier Janine Shepherd was nearly killed when she was hit by a truck during a training bike ride. Paralysed and immobile for six months, she was given a grim picture for recovery. But not only did she teach herself to walk again— she learned to fly.

Nancy Frates and her family have raised a projected $160 million for ALS research in 2014. How? They kicked off the ALS Ice Bucket Challenge to honor 29-year-old Pete Frates.