Klaus Stadlmann was pursuing his PhD at Vienna's Technical University when a broken laser system gave him some unexpected free time to think. Instead of working on his thesis, he decided to build the world's smallest 3D printer.

As a water scholar and protector, Kelsey Leonard seeks to establish Indigenous traditions of water conservation as the foundation for international water policy-making.

Chelsea Shields is a biocultural anthropologist, a research and strategy consultant, and an outspoken activist for women's rights.

Kelsey Johnson has spent her life in awe of the universe, and she works to inspire that awe in future generations.

William Collis strives to bring academic rigor and thought leadership to esports, which he believes will be the future of all human competition.

Severn Cullis-Suzuki is a lifelong environmental activist seeking justice for future generations.

Shukla Bose is the founder and head of the Parikrma Humanity Foundation, a nonprofit that runs four extraordinary schools for poor children.

Peter Diamandis runs the X Prize Foundation, which offers large cash incentive prizes to inventors who can solve grand challenges like space flight, low-cost mobile medical diagnostics and oil spill cleanup. He is the chair of Singularity University, which teaches executives and grad students about exponentially growing technologies.

António Guterres is at the forefront of fighting the climate emergency and achieving the Sustainable Development Goals.

Based in Bulgaria, Steve Keil creates companies around big social and environmental goals.

G.T. Bynum is using data-driven outcomes and trackable goals to break down historic lines of division.

Jamie Drummond co-founded the advocacy organization ONE, whose central themes are ending extreme poverty and fighting the AIDS pandemic.

Could good design save the newspaper -- at least for now? Jacek Utko thinks so -- and his lively, engaging designs for European papers prove that it works.

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.

Tolu Oyekan brings fresh thinking to how organizations can achieve their developmental goals in Africa and beyond.

Biotech entrepreneur Hadyn Parry leads a science start-up that develops GM insects to fight dengue fever.

Laura Trice is a counselor, life coach -- and purveyor of wholesome junk food.

Grace H. Kim is an internationally recognized expert in cohousing -- the art and craft of creating communities.

Margaret Mitchell is a senior research scientist in Google's Research & Machine Intelligence group, working on artificial intelligence.

At Sightsavers, an international NGO, Caroline Harper leads efforts to eliminate avoidable blindness around the world and fight for equal rights.

Makhtoum Abdalla is passionate about equal access to quality education for all children and young people.

Vanessa Nakate is the founder of the Rise Up Movement, which seeks to amplify the voices of climate activists in Africa.

Péter Fankhauser is the leader of a team of students working on Rezero, a robot that balances on a single sphere.

Cooperative enthusiast Anu Puusa wants to spread the word about co-ops -- and their potential as a sustainable business model that achieves long-term social, economic and environmental goals.

At MIT, Cynthia Breazeal and her team are building robots with social intelligence that communicate and learn the same way people do.

Environmentalist Jamie C. Beard is founder and executive director of the Geothermal Entrepreneurship Organization (GEO) at the University of Texas at Austin.

Marvin Minsky is one of the great pioneers of artificial intelligence -- and using computing metaphors to understand the human mind. His contributions to mathematics, robotics and computational linguistics are legendary and far-reaching.

Rodin Lyasoff makes improbable objects fly.

Achim Steiner is a global leader in sustainable development and international cooperation.

TED Fellow Joy Sun helped to launch a rare type of charity. GiveDirectly lets donors transfer money directly into the hands of impoverished people — empowering them to set their own goals and priorities.