Who is the only athlete who won the Athletics finals in the 400 and 800 m in the same Olympic Games?

Alberto Juantorena (born 3 December 1950) is a Cuban former runner. He is the only athlete to win both the 400 and 800 m Olympic titles, which he achieved in 1976. He was ranked as the world's best runner in the 400 m in 1974 and 1976–1978, and in the 800 m in 1976–77, and was chosen as the Track & Field News Athlete of the Year in 1976 and 1977.

Juantorena made it to the 800m Olympic final, and led the field for most of the race, eventually winning in a world record time of 1:43.50. He was the first non-English speaking athlete to win Olympic gold in this event. Three days later, he also won the 400 meter final, setting a low-altitude world record at 44.26. By winning the 400 meters, he became the first athlete since Paul Pilgrim at the 1906 Intercalated Games to do such a double at an Olympic sports event and was the only man to do so at an officially recognized Olympics.

This is acknowledged as a truly remarkable athletic accomplishment as the 400m is a sprint race and the 800m is a tactical middle-distance event.