Henry Fayol was a French engineer who made significant contributions to management theory. He distinguished between technical and managerial skills, identified core management functions, and developed principles of management. Some of the key principles he proposed included the division of work into smaller tasks for efficiency, ensuring authority is aligned with responsibility, maintaining discipline through rules and incentives, having a single reporting manager to avoid conflicting instructions, grouping activities with common objectives under one head, and prioritizing the interests of the organization over individual interests.