Extremely difficult to answer. What criteria do you use to judge? What events should be included? Should sprinters (Usain Bolt) or off roaders be included (Joss Naylor, Bob Graham) be included?
In no particular order:
Philippides (530 BC–490 BC), an Athenian herald or hemerodrome[2] (translated as "day-runner" (Kyle 2007),[5] "courier" (Larcher 1806),[6][7] "professional-running courier" (Sears 2003)[2] or "day-long runner" (Miller 2006)[8]), was sent to Sparta to request help when the Persians landed at Marathon, Greece. He ran about 240 km (150 mi) in two days. He then ran the 40 km (25 mi) from the battlefield near Marathon to Athens to announce the Greek victory over Persia in the Battle of Marathon (490 BC) with the word νικῶμεν (nikomen[9] "We win!"), as stated by Lucian chairete, nikomen ("hail, we are the winners")[10] and then collapsed and died.
Herbert James "Herb" Elliott AC MBE (born 25 February 1938) is a former Australian athlete and one of the world's greatest middle distance runners of his era. In August 1958 he set the world record in the mile run, clocking 3:54.5, 2.7 seconds under the record held by Derek Ibbotson; later in the month he set the 1500 metres world record, running 3.36.0, 2.1 seconds under the record held by Stanislav Jungwirth. In the 1500 metres at the 1960 Rome Olympics, he won the gold medal and bettered his own world record with a time of 3:35.6.
Few people have ever exercised such absolute authority in any branch of sport as Elliott did in middle distance running from 1957 to 1961. During that span he never lost a 1500 metres or 1-mile race.[2] During his career, he broke four minutes for the mile on 17 occasions.
Kenenisa Bekele (Amharic: ቀነኒሳ በቀለ; born 13 June 1982) is an Ethiopian long-distance runner, who holds the world record and Olympic record in both the 5,000 metres and 10,000 metres events. He won a double at the 2008 Summer Olympics in these events; he also won the 2004 Olympic title over 10,000 m.
He is the most accomplished runner in IAAF World Cross Country Championships history, with six long (12 km) course and five short (4 km) course titles. He won the 10,000 m title at the World Championships in Athletics four times running from 2003 to 2009 (matching Haile Gebrselassie's win streak). Kenenisa was unbeaten over 10,000 m from his debut in 2003 until 2011, when he failed to finish at the World Championships final.
At the 2009 World Championships in Athletics he became the first man to win both 5000 m and 10,000 m title at the same championships. Over 5000 m he has also won an Olympic silver (2004), World Championship bronze (2003), two African Championship titles and one All-Africa Games gold medal. He also won the 3000 metres title at the World Indoor Championships in 2006.
Kenenisa is considered one of the greatest distance runners of all time, owning several world records and an array of medals. On 6 April 2014, he produced the sixth fastest marathon debut ever on a record eligible course with his victory at the Paris Marathon, in a course record time of 2:05:04.
Haile Gebrselassie (Amharic: ኃይሌ ገብረ ሥላሴ?, haylē gebre silassē; born 18 April 1973) is a retired Ethiopian long-distance track and road running athlete. He won two Olympic gold medals over 10,000 metres and four World Championship titles in the event. He won the Berlin Marathon four times consecutively and also had three straight wins at the Dubai Marathon. Further to this, he won four world titles indoors and was the 2001 World Half Marathon Champion.
Haile had major competition wins at distances between 1500 metres and the marathon, moving from outdoor, indoor and cross country running to road running in the latter part of his career. He broke 61 Ethiopian national records ranging from 800 metres to the marathon, set 27 world records, and is widely regarded as the greatest distance runner in history.[2][3][4][5][6]
In September 2008, at the age of 35, he won the Berlin Marathon with a world record time of 2:03:59, breaking his own world record by 27 seconds. The record stood for three years. Since he was over the age of 35, that mark still stands as the Masters Age group world record.
Mohamed Muktar Jama "Mo" Farah, CBE (Somali: Maxamed Mukhtaar Jaamac Faarax) (born 23 March 1983) is a British distance runner.[11] On the track, he mostly competes over 5000 metres and 10,000 metres, but has run competitively from 1500 metres to the marathon.
The most successful British track athlete in modern Olympic Games history, he is the 2012 and 2016 Olympic gold medallist in both the 5000 m and 10,000 m. He is the second athlete in modern Olympic Games history, after Lasse Virén, to successfully defend the 5000 m and 10,000 m titles. Farah also completed the double at the 2013 and 2015 World Championships in Athletics. He was the second man in history to win long-distance doubles at successive Olympics and World Championships, and the first in history to do the quadruple-double.[12]
Born in Somalia, Farah moved to the UK as a child. He was originally based in London and ran for Newham and Essex Beagles athletics club, training at St Mary's University College, Twickenham from 2001 to 2011. Farah runs distance races tactically, but also can maintain a fast pace and has a quick sprint finish.
Farah is the European record holder for the 1500 m, 10,000 m, half marathon and two miles, the British record holder for the 5000 m, the European indoor record holder for 5000 m, the British indoor record in the 3000 m and the current indoor world record holder for the two miles.
He is the most decorated athlete in British athletics history, with nine global titles, and was the first British athlete to win two gold medals at the same world championships. His five gold medals at the European Athletics Championships make him the most successful individual athlete in championships history. He has won the European Athlete of the Year award and the British Athletics Writers Association British Athlete of the Year award more than any other athlete, three times and six times respectively. Farah was appointed Commander of the Order of the British Empire (CBE) in 2013.
IMHO MO needs some world records & he gets it!