Brian Leigh Maxwell (March 14, 1953 – March 19, 2004) was a Canadian track and field athlete, track coach, entrepreneur and philanthropist. He founded PowerBar, a maker of energy and nutritional products for athletes. Maxwell initially never intended to become a marathon runner, but lacked the speed necessary to be competitive at shorter distances. Despite being told as a teenager of his congenital heart condition, he persevered, and by 1977 he was ranked third among all marathoners in the world by Track and Field News. He died of a heart attack aged 51.