Morterone (Valassinese Lombard: Murterun) is a comune (municipality) in the Province of Lecco in the Italian region Lombardy, located about 50 kilometres (31 mi) northeast of Milan and about 7 kilometres (4 mi) northeast of Lecco. With a population of 33 people, it was considered the smallest of any comune (municipality) in Italy – in an area of 13.8 square kilometres (5.3 sq mi). For this record, it competes with the comune (municipality) of Pedesina, which in the past years had even fewer inhabitants. In 2016, Morterone with its 32 residents became the smallest Italian comune once again.

Morterone borders the following municipalities: Ballabio, Brumano, Cassina Valsassina, Cremeno, Lecco, Moggio, and Vedeseta.

The name Morterone derives from the Latin mortarium (pond) or murtus (myrtle).