Stefan Klein is a physicist, author, essayist, and visiting professor at Berlin University of the Arts. He was born on October 5, 1965. He is best known for his books The Science of Happiness and Time: A User's Guide. His works have been translated into 25 languages and became best sellers in many countries.

Klein studied physics and philosophy in Munich and Grenoble, and obtained a degree in biophysics in Freiburg. From 1996 to 1999, he headed the scientific information section of the weekly publication Der Spiegel and later GEO. In 1998, he received the prestigious Georg von Holtzbrinck Prize for Science Journalism.