Hermann Buhl was a mountain climber who became the first person to climb the 9th highest mountain in the world, Nanga Parbat. It was a solo climb. On his descent, he was caught in darkness and was forced to stand upright on a rock ledge for the entire night, in order to survive until morning.
Goran Kropp rode a bicycle 6,000 miles from Stockholm to the base of Mount Everest in 1996 with his mountain equipment, successfully climbed it solo and without bottled oxygen, and then cycled back home.
Due to many failed climbing expeditions, there are about 200 frozen human corpses near the top of Mount Everest. Retrieving the bodies is considered too dangerous.