Ralph Mosser Barnes (1900-1984) was an American industrial engineer who was a pioneer in motion and time study applications. Born in Clifton Mills, West Virginia, to John J. Barnes (1877-1963) and Martha Mosser (1975-1962), Barnes studied mechanical engineering at the University of West Virginia, where he received both his Bachelor of Sciences and Masters degrees. He then attended Cornell University, where he was reportedly the first person to ever receive a Ph.D. in industrial engineering.

At the beginning of his career, Barnes primarily worked in product development, lending his talents to companies such as U.S. Window Glass, Bausch & Lomb Optical, and Eastman Kodak. In 1928, he joined the University of Iowa as an Assistant Professor of Industrial Engineering, and by 1938 was serving as Director of the Department of Management. During his time at Iowa, Barnes and his students conducted a variety of observational experiments analyzing the performance of industrial manufacturing employees. Called motion and time studies, these experiments measured and rated an employee's efficiency while performing a repetitive task. After the study was complete, recommendations were made to management staff on what could be improved to increase productivity, such as employee body movement or position, equipment design, or time allowances. In 1937, Barnes published the book Motion and Time Study: Design and Measurement of Work and in 1941, he was awarded the Gilbreth Prize for his contributions to the field of industrial engineering.

In 1949, Barnes moved to the University of California, Los Angeles, where he taught industrial engineering until his retirement in 1968.