Lake Como (Lago di Como in Italian, also known as Lario; Lach de Comm in Insubric; Latin: Larius Lacus) is a lake of glacial origin in Lombardy, Italy. It has an area of 146 km², making it the third largest lake in Italy, after Lake Garda and Lake Maggiore. At over 400 m deep it is one of the deepest lakes in Europe and the bottom of the lake is more than 200 m below sea-level.

The lake is shaped much like the character “Y”. The northern branch begins at the town of Colico, while the towns of Como and Lecco sit at the ends of the southwestern and southeastern branches respectively. The small towns of Bellagio, Menaggio and Varenna are situated at the intersection of the three branches of the lake: a triangular boat service operates between them.

Lake Como is fed in large part by the Adda River, which enters the lake near Colico and flows out at Lecco. This geological conformation makes the southwestern branch a dead end, and so Como, unlike Lecco, is often flooded.

The mountainous pre-alpine territory between the two southern arms of the lake—between Como, Bellagio and Lecco—is known as the Larian Triangle, or Triangolo lariano. The source of the river Lambro is here. At the centre of the triangle, the town of Canzo is the seat of the Comunità montana del Triangolo Lariano, an association of the 31 municipalities which represent the 71,000 inhabitants of the area.

The lake's name in Latin is Larius, Italianized as Lario, but this name is rarely used; it is usually called Lago di Como (literally "Lake of Como"). In guidebooks the lake may be variously described as "Lake Como", "Lake of Como", or "Como Lake." The lake's name comes from the town of Como, known to the Romans as Comum.

While the town of Como is referred to as "Como," the lake itself is never referred to solely by this name. (This is not true of another lake in Italy, Lake Garda, where "Garda" may refer to either a town on its shores, or the lake).