John Delphus "J.D." McDuffie, Jr. (December 5, 1938 – August 11, 1991) was an American racing driver who competed in the NASCAR Winston Cup Series from 1963 to 1991 and collecting 106 Top 10 finishes during his career. He holding the record for most starts in NASCAR's top level without a win.

McDuffie was involved in an accident on the fifth lap of the 1991 Budweiser at The Glen race at Watkins Glen International. On the straight between the esses and the loop-chute, at 170 mph, McDuffie collided with Jimmy Means after suffering a mechanical failure.

McDuffie's left front wheel spindle broke off of the car, causing him to lose brakes and hit Means in the right front. This left him no way of stopping the car or steering it, and to further complicate matters, there was no gravel trap in the corner that McDuffie was headed toward. As a result, McDuffie skidded across the grass and hit the outside retaining wall and tire barrier with such force that the car shot into the air, rotated, and then came to rest upside-down.

Means also crashed into the same corner but was able to slow his vehicle down before the impact; his car went under McDuffie's as it was in mid-air. Means, a fellow independent racer, suffered only minor cuts and bruises in the accident, and got out of his car to check on McDuffie.

After peering into McDuffie's car, he began frantically signaling for assistance, and a host of medical personnel and track workers rushed to the scene.

The race was delayed for two hours as McDuffie was removed from his car and his Pontiac was removed from the infield. Also, the wall that McDuffie and Means struck had to be repaired. As the cars got back on the track and cruised under yellow flag conditions, the media attention turned to Chip Williams, NASCAR's PR director, who disclosed that McDuffie had lost his life in the accident.

He had died instantly from head and brain injuries. The direct cause of death was a basilar skull fracture caused by rapid head movement to the right.