David Allen is an American productivity consultant and author, best known for his book, Getting Things Done (GTD). He developed the GTD methodology, which focuses on organizing tasks and projects to reduce stress and increase efficiency. His approach emphasizes capturing all tasks in a reliable system, allowing individuals to focus on their work without mental clutter. Allen founded the David Allen Company, which offers training and resources for individuals and organizations seeking to improve their productivity. His work has influenced many professionals and has been adopted by various industries, making him a prominent figure in the field of personal and organizational productivity.