The Eastern Oyster Crassostrea virginica is a species of oyster that is found on the eastern seaboard of North America. It is also known as the American Oyster or the Virginia Oyster.

The Eastern Oyster is found from the Gulf of St Lawrence to the Gulf of Mexico. It has been introduced elsewhere but does not always thrive (for example, a colony in San Francisco Bay died out).

Like all oysters, Crassostrea virginica is a hard shellfish that comes in several different sizes, usually 5 to 15 cm (2 to 6 inches) long. It has hard edges that supply a tough shield against predators. They are popular on the market, so much so that only 1% remain of their original numbers when the early colonists came to America during the sixteenth century.

Many people don't realize that these particular type of oysters have an important environmental value. Like all oysters, Crassostrea virginica is a filter feeder. They suck in water and filter out the plankton and detritus to swallow, then spit the water back out, thus cleaning the water around them and getting rid of much of eastern Chesapeake Bay's notorious water pollution.

People catch and eat these oysters, mainly in the spring, and (in Maryland) catch about 35,000 to 40,000 bushels (1,200 to 1,400 m³) of oysters a year. This has resulted in the decline of the numbers of C. virginica.

"Dermo" (Perkinsus marinus) is marine disease of oysters, caused by a protozoan parasite. It is a prevalent pathogen of oysters, causing massive mortality in oyster populations and poses a significant economic threat to the oyster industry.

The Eastern Oysters, like all members of the family Ostreidae, can make small pearls to surround particles that enter the shell. However these pearls are insignificant in size and of no value; the Pearl Oyster, from which commercial pearls are harvested, is of a different family.