Frederick Herzberg was a prominent American psychologist known for developing the two-factor theory of motivation, which distinguishes between intrinsic motivators and extrinsic hygiene factors affecting employee satisfaction. His theory emphasizes that while hygiene factors are necessary to prevent dissatisfaction, true motivation comes from factors like achievement, recognition, and growth opportunities. Despite its influence, the theory has faced criticism for overlooking certain situational variables and the unique perspectives of blue-collar workers.