The largemouth bass (Micropterus salmoides) is a carnivorous freshwater gamefish in the Centrarchidae (sunfish) family, a species of black bass native to the eastern and central United States, southeastern Canada and northern Mexico, but widely introduced elsewhere. It is known by a variety of regional names, such as the widemouth bass, bigmouth bass, black bass, bucketmouth, largies, Potter's fish, Florida bass, Florida largemouth, green bass, bucketmouth bass, Green trout, gilsdorf bass, Oswego bass, LMB, and southern largemouth and northern largemouth. The largemouth bass is the state fish of Georgia and Mississippi, and the state freshwater fish of Florida and Alabama.

The largemouth bass, an olive-green to greenish-gray fish, was first described by French naturalist Bernard Germain de Lacépède in 1802. Recent studies have concluded that the correct binomial name for the Florida bass is Labrus salmoides, while the oldest available binomial for the largemouth bass is Cuvier's Huro nigricans. The largemouth bass is the largest of the black basses, with a maximum recorded length of 29.5 inches and an unofficial weight of 25 pounds 1 ounce.

Their diet includes smaller fish, shad, worms, snails, crawfish, frogs, snakes, and salamanders. They prefer habitats with abundant littoral vegetation and have a lifespan of 10 to 16 years in the wild. Largemouth bass spawn in the spring when water temperatures reach above 60°F. They are popular among anglers for their vigorous resistance when caught.

Largemouth bass have been introduced to many regions due to their popularity as a sport fish and tolerance to urban environments. However, they have become an invasive species in some areas, causing the decline, displacement, or extinction of native species through predation and competition.