Joseph Weider (/ˈwiːdər/; November 29, 1919 – March 23, 2013) was a Canadian bodybuilder and entrepreneur who co-founded the International Federation of BodyBuilders (IFBB) alongside his brother Ben Weider. He was also the creator of the Mr. Olympia, the Ms. Olympia and the Masters Olympia bodybuilding contests. He was the publisher of several bodybuilding and fitness-related magazines, most notably Muscle & Fitness, Flex, Men's Fitness and Shape, and the manufacturer of a line of fitness equipment and fitness supplements.
Weider was born in Montreal, Quebec, Canada, to Louis and Anna Weider, Polish Jewish emigrants from the town of Kurów, Poland. He published the first issue of Your Physique magazine in 1940, and built a set of barbells out of car wheels and axles the same year out of the family garage on Coloniale Street in Montreal. He designed numerous training courses beginning in the 1950s, including the Weider System of Bodybuilding.