Ruth Chepng'etich, often spelled Ruth Chepngetich, is a Kenyan road racing athlete, who competes in the marathon and other long distance events. She was the 2019 Marathon World champion in hot and humid conditions. Chepng'etich twice won the Chicago Marathon, in 2021 and 2022. Her personal best in the marathon sits second on the world's all-time list. She holds the third-fastest mark of all time for the half marathon.

The women's marathon was one of the road events at the 2019 World Athletics Championships in Doha, Qatar. Due to the heat in Doha, the race was scheduled to begin at 23:59 on 27 September 2019, which made it the first midnight marathon in the history of the World Championships. Even with the unusual timing, the temperature was above 30 °C (86 °F) and the humidity over 70 per cent, making conditions difficult for running. Only 40 of the 68 entrants finished the race, which was won by Ruth Chepng'etich of Kenya in 2:32.43; the slowest winning time at the World Championships. Bahrain's Rose Chelimo was second in 2:33.46, with Helalia Johannes of Namibia third in 2:34.15.