| Jean ALT | |
| Birth Date: | 8 August 1921 |
| Birth Place: | Paris, France |
| Death Date: | 22 July 1991 |
| Death Place: | Savigny-sur-Orge, France |
| Occupation: | Scientist, Meteorologist, Polar explorer |
| Known For: | Alt Glacier |
| Nationality: | French |
| Children: | 4 |
Jean Alt (8 August 1921 – 22 July 1991) was a French scientist and meteorologist. He was born in Paris.
Alt was a scientist of the IGY. He took part in the American mission Deep Freeze III in Little America V (an Antarctica base) during the winter of 1958. He stayed 16 months in Antarctica.
He was part of the little America V team in the same period that Albert P. Crary
Later the Advisory Committee on Antarctic Names gave his name to a glacier: the Alt Glacier