Clayton M. Christensen (1952?2020) is one of the best-known and most influential thinkers on innovation theory and practice. His research led to one of the most important ideas of the century?disruptive innovation. As a professor at Harvard Business School, he influenced generations of leaders and entrepreneurs. He authored twelve books, including five New York Times bestsellers, and over one hundred articles on disruptive innovation in business, healthcare, and education. Christensen cofounded Innosight, a management consultancy; Rose Park Advisors, an investment firm; and the Clayton Christensen Institute, a nonprofit think tank. He was a friend and mentor to some of the most important innovators of our time.