The 1966 Southern 500, the 17th running of the event, was a NASCAR Grand National Series event that was held on September 5, 1966, at Darlington Raceway in Darlington, South Carolina.

Lonnie "LeeRoy" Yarbrough was an American stock car racer. His best season was 1969 when he won seven races, tallied 21 finishes in the top-ten and earned $193,211. During his entire career from 1960–1972, he competed in 198 races, scoring fourteen wins, 65 finishes in the top-five, 92 finishes in the top-ten, and ten pole positions. Yarbrough also competed in open-wheel racing, making 5 starts in the USAC Championship cars, including 3 Indianapolis 500s, with a best finish of 3rd at Trenton Speedway in 1970. His racing number was 98. When asked about his passion, Yarbrough described racing as "what I call my life."