An ultramarathon (also called ultra distance) is any sporting event involving running longer than the traditional marathon length of 42.195 kilometres (26.2188 mi).

There are two types of ultramarathon events: those that cover a specified distance, and events that take place during specified time (with the winner covering the most distance in that time). The most common distances are 50 kilometres (31.069 mi), 100 kilometres (62.137 mi), 50 miles (80.467 km) and 100 miles (160.934 km), although many races have other distances. The 100 kilometers is an official IAAF world record event.

Other distances/times include double marathons, 24-hour races, and multiday races of 1000 miles or even longer. The format of these events and the courses vary, ranging from single or multiple loops (some as short as a 400-meter track), to point-to-point road or trail races, to cross-country rogaines. Many ultramarathons, especially trail challenges, have severe course obstacles, such as inclement weather, elevation change, or rugged terrain. Many of these races are run on dirt roads or mountain paths, though some are run on paved roads as well. Usually, there are aid stations every 20 to 35 km apart, where runners can replenish food and drink supplies or take a short break.

Dean Karnazes (b. Constantine Karnazes August 23, 1962) (pronounced car-NAH-sis), is an American ultramarathon runner, and author of Ultramarathon Man: Confessions of an All Night Runner, which details ultra endurance running for the general public. Karnazes has been described as "the world's most famous ultramarathon runner."

Karnazes grew up in Los Angeles, California, to parents of Greek ancestry. During kindergarten, Karnazes began running home from school; he took up running so that he would not have to burden his mother with rides home from school every day.

At first, Karnazes ran direct routes from school to his home. Later, he began to run diversionary routes that would extend his run and take him into uncharted territory. By third grade he was participating in and organizing short running events with other kids. As Karnazes grew older, he began testing his limits: by age eleven he had hiked rim-to-rim across the Grand Canyon and had climbed Mount Whitney, the highest mountain in the contiguous United States; for his 12th birthday, he cycled 40 miles (64 km) to his grandparents' home for fun without telling his parents.

Hannah Roberts is a British cellist best known for her duets with her husband, pianist Simon Parkin. They are well known as Simon's music is often played on the BBC. Roberts is currently a cello professor at the Royal Northern College of Music in Manchester, UK.