Henry "Harry" Green (1886–1934) was a British long-distance runner active during the early 20th century. He is best known for briefly holding the world record for the marathon and representing Great Britain in international competition.
Green was a member of the Herne Hill Harriers, an athletics club based in South London. His most significant athletic achievement occurred on May 12, 1913, at the Polytechnic Marathon. Running the course from Windsor to Chiswick, Green finished with a time of 2 hours, 38 minutes, and 16.2 seconds. This performance was recognized as a world record by the International Association of Athletics Federations (IAAF), which had begun formalizing record-keeping for the event around that period. His record stood for nineteen days before it was surpassed by the Swedish runner Alexis Ahlgren on May 31, 1913.
Prior to his world record performance, Green competed in the marathon at the 1912 Summer Olympics in Stockholm, Sweden. He was among the participants who failed to finish the race due to the difficult conditions and high temperatures.
Outside of his athletic pursuits, Green was a bootmaker by trade. He died in March 1934 at the age of 47. His contributions to the sport are primarily cited in the historical progression of marathon world records and the early history of British distance running.