The West Island is the unofficial name given to the former, mostly suburban municipalities of Baie-d'Urfe, Beaconsfield, Dollard-des-Ormeaux, Dorval, Kirkland, Lachine, Ile-Bizard, Pierrefonds, Pointe-Claire, Roxboro, Sainte-Anne-de-Bellevue, Sainte-Genevieve, and Senneville, which comprise the western half of the Island of Montreal, in Quebec, Canada. The West Island's population is approximately 250,000 and, although most of its residents are bilingual, it has traditionally attracted English-speaking residents. These 13 municipalities have since been amalgamated into the city of Montreal, despite local opposition to the merger.

The name probably originated from the geolingustic division of the island into French and English, with francophones typically inhabiting the eastern portion of the island and anglophones typically inhabiting the western half. While this division does not necessarily apply today, anglophones still make up the majority of the West Island population.

The West Island is sometimes derogatorily referred to as the "Waste Island," because urban Montrealers tend to see it as a suburban wasteland, devoid of cultural attractions, and most of its residents go to downtown Montreal for such activities. This was used as an argument for amalgamation, as West Islanders enjoyed lower taxes than the old city of Montreal, but still used its theatres, concert halls, and museums. With amalgamation, tax rates have been harmonized across the island.

The region is home to the Montreal-Pierre Elliott Trudeau International Airport (formerly Montreal-Dorval), John Abbott College, and the Macdonald Campus of McGill University.