Reinhold Andreas Messner (German pronunciation: [anhlt msn]) (born 17 September 1944) is an Italian mountaineer, explorer, and author from South Tyrol. He made the first solo ascent of Mount Everest and, along with Peter Habeler, the first ascent of Everest without supplemental oxygen. He was the first climber to ascend all fourteen peaks over 8,000 metres (26,000 ft) above sea level. Messner was the first to cross Antarctica and Greenland with neither snowmobiles nor dog sleds. He also crossed the Gobi Desert alone. He is widely considered one of the best mountaineers of all times.

From 1999 to 2004, Messner served as a member of the European Parliament for north-east Italy, as a member of the Federation of the Greens.

Messner has published more than 80 books about his experiences as a climber and explorer. In 2018, he received jointly with Krzysztof Wielicki the Princess of Asturias Award in the category of Sports.

Mount Everest (Nepali: सगरमाथा, romanized: Sagarmāthā; Tibetan: Chomolungma ཇོ་མོ་གླང་མ; Chinese: 珠穆朗玛峰; pinyin: Zhūmùlǎngmǎ Fēng) is Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas. The China–Nepal border runs across its summit point. Its elevation (snow height) of 8,848.86 m (29,031.7 ft) was most recently established in 2020 by the Chinese and Nepali authorities.Mount Everest attracts many climbers, including highly experienced mountaineers. There are two main climbing routes, one approaching the summit from the southeast in Nepal (known as the "standard route") and the other from the north in Tibet. While not posing substantial technical climbing challenges on the standard route, Everest presents dangers such as altitude sickness, weather, and wind, as well as hazards from avalanches and the Khumbu Icefall. As of 2019, over 300 people have died on Everest, many of whose bodies remain on the mountain.The first recorded efforts to reach Everest's summit were made by British mountaineers. As Nepal did not allow foreigners to enter the country at the time, the British made several attempts on the north ridge route from the Tibetan side. After the first reconnaissance expedition by the British in 1921 reached 7,000 m (22,970 ft) on the North Col, the 1922 expedition pushed the north ridge route up to 8,320 m (27,300 ft), marking the first time a human had climbed above 8,000 m (26,247 ft). The 1924 expedition resulted in one of the greatest mysteries on Everest to this day: George Mallory and Andrew Irvine made a final summit attempt on 8 June but never returned, sparking debate as to whether they were the first to reach the top. Tenzing Norgay and Edmund Hillary made the first official ascent of Everest in 1953, using the southeast ridge route. Norgay had reached 8,595 m (28,199 ft) the previous year as a member of the 1952 Swiss expedition. The Chinese mountaineering team of Wang Fuzhou, Gonpo, and Qu Yinhua made the first reported ascent of the peak from the north ridge on 25 May 1960.