Kenneth Ray Sprague (born July 14, 1945) is an American bodybuilder, entrepreneur, author, and educator best known for purchasing and operating the original Gold's Gym in Venice, California, from 1970 to 1979, during which time it emerged as the epicenter of the golden era of bodybuilding and hosted events featured in the documentary Pumping Iron. Under his ownership, the gym attracted elite athletes including Arnold Schwarzenegger, grew its annual revenue significantly from modest beginnings, and gained national media attention through coverage in outlets like 60 Minutes and the Wall Street Journal. Sprague, who began weight training in childhood and competed in bodybuilding, powerlifting, and track and field events, later authored several instructional books on strength training, such as The Gold’s Gym Strength Training Book (1994) and The Gold’s Gym Bodybuilding Book (1983), drawing from his experiences coaching adolescent athletes and world champions across multiple sports. His tenure at Gold's Gym played a key role in popularizing weight training, though Sprague has noted in interviews being underrepresented in mainstream narratives of the era.