Who was the first climber to summit all 14 eight-thousanders?

Reinhold Messner was the first climber to summit all 14 eight-thousanders.

The eight-thousanders are the 14 independent mountains higher than 8,000 metres above sea level, all located in the Himalayas or Karakoram. Messner completed the collection on Lhotse in 1986, becoming the first person to reach the summit of every mountain in the group. His achievement was especially notable because he climbed without supplemental oxygen.

Messner began the project with Nanga Parbat in 1970 and completed his climbs over 16 years. He and Peter Habeler had earlier become the first people to climb Mount Everest without supplemental oxygen, in 1978. Messner also helped popularize demanding alpine-style climbing rather than relying on large fixed expeditions.

Polish climber Jerzy Kukuczka became the second person to complete all 14, in 1987. Nirmal Purja later set a speed record for climbing all 14, completing them in 2019, but he was not the first.