Eric Arthur Heiden (born June 14, 1958) is an American physician and a former long track speed skater, road cyclist and track cyclist. He won an unprecedented five individual gold medals, and set four Olympic records and one world record at the 1980 Winter Olympics. Heiden was the most successful athlete at those Olympic Games, single-handedly winning more gold medals than all nations except for the Soviet Union (10) and East Germany (9). He is the most successful Winter Olympian from a single edition of any Winter Olympics. He delivered the Athlete's Oath at those same 1980 Games. His coach was Dianne Holum.

Heiden is an icon in the speed skating community. His victories are significant, as few speed skaters (and athletes in general) have won competitions in both sprint and long-distance events. Heiden is the only athlete in the history of speed skating to have won all five events in a single Olympic tournament and the only one to have won a gold medal in all events. He is considered by some to be the best overall speed skater (short and long distances) in the sport's history. Heiden ranked No. 46 in ESPN's SportsCentury 50 Greatest Athletes of the 20th Century in 1999, the only speed skater to make the list. In 2000, a Dutch newspaper called him the greatest skater ever.

Heiden was born in Madison, Wisconsin on June 14, 1958. His father, Jack Heiden, was a longtime orthopedic surgeon in Madison. His sister, Beth Heiden, also became an accomplished cyclist, speed skater and cross-country skier. In their hometown Shorewood Hills, Wisconsin (a suburb of Madison), Eric and his sister Beth were the driving forces behind the creation of the Heiden Haus, a small outpost where local children can warm up after skating or playing hockey on the ice rink (complete with underground clay platform). He graduated from Madison West High School in 1976.

After starting his undergraduate education at the University of Wisconsin–Madison, Heiden transferred to the University of California, San Diego and then to Stanford University in California, earning a B.S. degree in 1984 and an M.D. degree in 1991.

Heiden won the World Junior Speed Skating Championships in 1977 and 1978. During his short speed skating career, Heiden won three World Allround Championships and four World Sprint Championships, becoming the youngest athlete to do so. Three times he broke the world record in the 1000 metres, twice in the 3000 metres, and once each in the 1500 metres and 10000 metres. He also broke the points world record in both allround and the sprinting distances.

Heiden finished his speed skating career by finishing second behind Hilbert van der Duim at the 1980 World Allround Championships in Heerenveen. He stood at the top of the Adelskalender, a ranking system for long-track speed skating, for a record 1,495 days, and he won the Oscar Mathisen Award four times in a row from 1977 until 1980. As of 2025, he still is the only skater who has won the award four times.

He received the 1980 James E. Sullivan Award as the top amateur athlete in the United States. In 1983, he was inducted into the United States Olympic Hall of Fame.

Heiden was elected to the Wisconsin Athletic Hall of Fame in 1990.