thumb|300px|[[Jules Jacot-Guillarmod, Charles-Adolphe Reymond and Alcesti C. Rigo De Righi (from left to right) at the base camp of Kanchenjunga Expedition]]
The 1905 Kanchenjunga expedition was a Himalayan mountaineering expedition aimed to climb to the summit of the third-highest mountain in the world, Kangchenjunga, which would ultimately only be achieved in 1955.
The expedition was an idea of the Swiss doctor and photographer Jules Jacot-Guillarmod. In April 1905 he proposed his plans to the British occultist Aleister Crowley, with whom he had participated in Oscar Eckenstein's K2 expedition in 1902. Crowley agreed to join the expedition because as the climbing leader he would have the opportunity to break the altitude record. The record at the time was held by either William Woodman Graham, Emil Boss and Ulrich Kaufmann on Kabru (7,315 m), a widely contested, but possibly accurate claim, or Matthias Zurbriggen on Aconcagua (6,962 m).
Jacot-Guillarmod recruited two of his countrymen, Alexis Pache and Charles-Adolphe Reymond, while Crowley recruited his hotelkeeper in Darjeeling, the young Italian Alcesti C. Rigo de Righi, as transport officer. On July 31 the five left with three Kashmiri servants (who had been in the K2 expedition as well), and about 230 local porters. Armed with Douglas Freshfield's map of the range and Vittorio Sella's pictures, created during a circumnavigation of the massif in 1899, Crowley planned to climb the southwest face of Kanchenjunga over the Yalung Glacier. When Camp IV was made above this glacier, the team had fallen apart: Jacot-Guillarmod especially was shocked by Crowley's arrogant behavior and brutal treatment of the (barefooted) porters. Camp V was still made around 6,200 m, and on September 1, Crowley, Pache, Reymond and a group of porters made it to about 6,500 m before a small avalanche forced a nervous retreat.