A railroad car, railcar (American and Canadian English), railway wagon, railway carriage, railway truck, railwagon, railcarriage or railtruck (British English and UIC), also called a train car, train wagon, train carriage or train truck, is a vehicle used for the carrying of cargo or passengers on a rail transport network (a railroad/railway). Such cars, when coupled together and hauled by one or more locomotives, form a train. Alternatively, some passenger cars are self-propelled in which case they may be either single railcars or make up multiple units.

The term "car" is commonly used by itself in American English when a rail context is implicit. Indian English sometimes uses "bogie" in the same manner, though the term has other meanings in other variants of English. In American English, "railcar" is a generic term for a railway vehicle; in other countries "railcar" refers specifically to a self-propelled, powered, railway vehicle.

Although some cars exist for the railroad's own use – for track maintenance purposes, for example – most carry a revenue-earning load of passengers or freight, and may be classified accordingly as passenger cars or coaches on the one hand or freight cars (or wagons) on the other.