Widely regarded as Britain's greatest ever Olympian, the length of time that rower Sir Steve Redgrave spent at the top of his game is almost unprecedented. To win a gold medal at one Olympic Games is an achievement, but to win a gold medal in five consecutive Olympic Games is unheard of, and Redgrave is the only person to have done so in an endurance sport. Maintaining a world-class level of performance for 20 years is an outstanding achievement, and has earned Redgrave a well-deserved knighthood.

Few are well-known by their first names, but Nadia Comaneci is, as she was such a household name in her time. Discovered at just six years old, Comaneci was the first gymnast to achieve a perfect score of 10 within the Olympic games. A winner of many gold Olympic medals, her name is still synonymous with the perfect 10. She’s also the world record holder of the youngest gymnastics all-around Olympic champion.

American swimmer Michael Phelps is the most decorated Olympian of all time. Over the course of three Olympic Games, Phelps amassed an unprecedented 18 gold medals, which is twice the haul of the second-highest record holders in the sport. Unsurprisingly, his outstanding success also meant he was the most successful athlete in each of the three Olympics he competed in.

Roger Federer is widely regarded as the greatest men’s tennis player of all time and has continuously been ranked in the top 10 since 2002. The list of records that Federer holds is almost endless, but highlights include winning 20 Grand Slam singles titles, reaching each Grand Slam final at least five times and holding the world no. 1 position for 310 weeks.

9.58 seconds is the record-breaking time in which Usain Bolt ran the 100 metres at the 2009 World Championships. In the 2008 Beijing Olympics, he won the 200 metres and 4x100 metres relay, setting world records in both. Four years later at the London Olympics, Bolt won gold in all three once again, setting another world record in the 4x100 metres relay. Bolt's unrivalled speed has helped him smash world records that some thought would never be beaten.

Muhammad Ali is often regarded as the greatest sportsperson of all time. Ali competed in some of the greatest fights in boxing history, including the 'Fight of the Century', 'Rumble in the Jungle' and 'Thrilla in Manila'. He was famous for his political stances, and was stripped of his heavyweight title after refusing to be conscripted into the US military to fight in the Vietnam War. Arguably more famous than all of this, however, are his timeless quotes. "Floats like a butterfly, sting like a bee" is among the dozens of one-liners that Ali is famous for. But perhaps the quote that best sums up Muhammad Ali is: "I'm not the greatest; I'm the double greatest. Not only do I knock 'em out, I pick the round."

As a record three-time World Cup winner, Pelé holds the world record for the most career goals in football (an astonishing 1283 goals in 1363 games). Pelé spent the vast majority of his career playing for the Brazilian club Santos, but the end of his career saw him play three seasons with the New York Cosmos. Pelé helped put football on the map in America and brought the sport to the masses.

American tennis superstar Serena Williams has won more Grand Slam singles titles than any other player – male or female – throughout the Open Era. Through her powerful style of play, she has revolutionised women’s tennis and has faced countless obstacles during her career – such as unwarranted criticism, racism and competition in the sport against her older sister Venus Williams.

Michael Jordan is commonly regarded as basketball's greatest ever player. Although the sport is most popular in the United States, Jordan is a household name across the globe. In 1999 he was named the greatest athlete of the 20th century by ESPN, achieving the bulk of his success while playing for the Chicago Bulls. Jordan is a six-time NBA champion and a five-time NBA Most Valuable Player, with a host of other accolades to his name.

Turning professional in 1982 at just 13 years old, Steffi Graf is one of history’s greatest tennis players. She was the second-youngest player to earn an international ranking, and in 1987 became the world’s number one female tennis player, a title she held for 377 weeks over her career. Dominating the sport from 1987–1999, Graf won 22 Grand Slams – more than anyone in the sport at the time.