Burrhus Frederic Skinner (March 20, 1904 – August 18, 1990) was a highly influential American psychologist, behaviorist, inventor, and social philosopher. He served as the Edgar Pierce Professor of Psychology at Harvard University from 1958 until his retirement in 1974.

Skinner developed behavior analysis, particularly the philosophy of radical behaviorism, and founded the experimental analysis of behavior, a school of experimental research psychology. He utilized operant conditioning to strengthen behavior, considering the rate of response to be the most effective measure of response strength. To study operant conditioning, he invented the operant conditioning chamber (also known as the Skinner box), and to measure rate, he invented the cumulative recorder. Through these tools, he and Charles Ferster produced Skinner's most influential experimental work, outlined in their 1957 book Schedules of Reinforcement.

Skinner was a prolific author, publishing 21 books and 180 articles. He envisaged applying his ideas to the design of a human community in his 1948 utopian novel, Walden Two, while his analysis of human behavior culminated in his 1958 work, Verbal Behavior.

Together with John B. Watson and Ivan Pavlov, Skinner is considered a pioneer of modern behaviorism. In a survey conducted in June 2002, Skinner was recognized as the most influential psychologist of the 20th century.