John Adair is a British leadership theorist and author, best known for his work on leadership and management. He developed the concept of the Action-Centred Leadership model, which emphasizes the importance of balancing three key elements: task, team, and individual. His ideas have influenced many leaders and organizations around the world. Adair has written numerous books on leadership, including Not Bosses But Leaders and The Leadership of Muhammad. He has also served as a consultant and trainer, helping various organizations improve their leadership practices. His contributions have made a significant impact on the field of leadership studies.