The Lepontii were an ancient people occupying portions of Raetia (in modern Switzerland and Italy) in the Alps during the time of the Roman conquest of that territory. The Lepontii have been variously described as a Celtic, Raetian, and German tribe, but insufficient data remains to categorize them definitively.

The chief town of the Lepontii was Oscela, now Domodossola, Italy, and their territory included the Southern slopes of the Saint Gothard Pass and the Simplon Pass and the headwaters of the Rhine River.