Mario Fantin (Bologna, 9 May 1921 – Bologna, 23 July 1980) was an Italian mountaineer and film director. Born to Friulian parents, he graduated in accounting in 1940.

In February 1941 he went into military service and took part in the fighting of the Second World War in Albania, Kosovo and Montenegro with the rank of second lieutenant. He returned to Italy at the end of 1944, severely affected by the immense tragedy of the "Division of Venice". At the end of 1946 he enrolled in the Bologna section of the Italian Alpine Club and, after taking a mountaineering course, he began to frequent the Alps, documenting his ascents with his camera: this would be the beginning of a long adventure as a mountaineer, photographer and filmmaker.

In the late 1940s he began his career as a nature documentary filmmaker. In 1954 he took part in the Italian expedition to conquer K2, led by Ardito Desio, as a photographer and director of photography to produce photographic and cinematographic documentation of the undertaking. He reached an altitude of about 6,000 metres. From the documentation collected with Achille Compagnoni, the director Marcello Baldi made the film Italia K2. During the expedition he also wrote the diary “K2 Sogno vivere”, published about three years later.

After returning from this undertaking, he devoted himself full-time to the mountains and ethnography: he took part in 33 extra-European expeditions, including 20 mountaineering expeditions, including in the Andes, the Sahara, equatorial Africa and Greenland; On these occasions he made 47 documentary films, with soundtracks in five languages, on the mountains and on the ethnography of the peoples and peoples he met during his travels. He also took several thousand photographs and published over 20 monographic works and a hundred publications on Italian mountaineering in the world, on the exploration and ethnography of all continents.

His passion for documentary led him in 1967 to found in Bologna the Centro Italiano Studio Documentazione Alpinismo Extraeuropeo (CISDAE), today based in Turin at the Italian Alpine Club, with the declared objective of "collecting, preserving, processing, enhancing, studying and publishing 'what refers to Italian mountaineering in the world and to foreign mountaineering'; it constitutes the most important Italian and world collection of documents on what has been achieved in the field of extra-European mountaineering. Using the vast archives of the CISDAE, which he continually fed with new documentation (at his death they contained tens of thousands of photographs, documents, data, maps, testimonies), Mario Fantin devoted himself to writing bibliographical works on Italian mountaineering in the world, on the mountains and glaciers of Africa and Greenland, on the indigenous populations of various parts of the world, etc. The Center was acquired in 1973 by the Italian Alpine Club, which left it under Fantin's management.

Tormented by personal and health problems, as well as by depression, Mario Fantin committed suicide on July 23, 1980.

After his death, the Bologna section of the CAI was dedicated to him.