Jacques Poincenot, born in 1923 and drowned on December 27, 1951 in the Río Fitz Roy, is a French mountaineer. After the Second World War, he was one of the best climbers in the forest of Fontainebleau, around the "master" Pierre Allain: René Ferlet, Guido Magnone, Jean Couzy, Auguste Fix etc.

In 1946, he took part in the 3rd ascent of the Walker route to the Grandes Jorasses. The following year, in 1947, he took part in Alain Pol's short film Attacking the Eiffel Tower (23 min, in black and white), in which the ascent of the Eiffel Tower is filmed by the same group of mountaineers who had climbed the Grandes Jorasses. The film won the Louis Lumière prize in 19484 and was rewarded at the Venice Biennale. Participating in the French expedition of 1951-1952 for the conquest of Fitz Roy with in particular Lionel Terray, Guido Magnone and Marc Antonin Azéma (who wrote the story), he died during the long access march, by drowning in the río Fitz Roy, then in flood. He is buried in the cemetery of Puerto Santa Cruz.

To honor his memory, his name was given to a peak close to Fitz Roy, the Poincenot needle (3,002 m, in Spanish: Aguja Poincenot). The base camp for access to Fitz Roy and nearby hikes also bears his name. In Fontainebleau, a boulder passage bears his name in the Trois Pignons forest (southern part of the Bellifontain complex). At the very famous site of 95.2, on the white circuit, La Poincenot, rating 6c.