Jeremy Matthew Wariner is a retired American track athlete specializing in the 400 meters. He has won four Olympic medals and six World Championships medals. He is the fourth fastest competitor in the history of the 400 m event with a personal best of 43.45 seconds, behind Wayde van Niekerk, Michael Johnson and Butch Reynolds and the fifth fastest all-time mark when he set it in 2007.

The 400 metres, or 400-meter dash, is a sprint event in track and field competitions. It has been featured in the athletics programme at the Summer Olympics since 1896 for men and since 1964 for women. On a standard outdoor running track, it is one lap around the track. Runners start in staggered positions and race in separate lanes for the entire course. In many countries, athletes previously competed in the 440-yard dash (402.336 m)—which is a quarter of a mile and was referred to as the "quarter-mile"—instead of the 400 m (437.445 yards), though this distance is now obsolete.