A railcar (not to be confused with a railway car) is a self-propelled railway vehicle designed to transport passengers. The term "railcar" is usually used in reference to a train consisting of a single coach (carriage, car), with a driver's cab at one or both ends. Some railway companies, such as the Great Western, termed such vehicles "railmotors" (or "rail motors").

Self-propelled passenger vehicles also capable of hauling a train are, in technical rail usage, more usually called "rail motor coaches" or "motor cars" (not to be confused with the motor cars, otherwise known as automobiles, that operate on roads).

The term is sometimes also used as an alternative name for the small types of multiple unit which consist of more than one coach. That is the general usage nowadays in Ireland when referring to any diesel multiple unit (DMU), or in some cases electric multiple unit (EMU).

In North America the term "railcar" has a much broader sense and can be used (as an abbreviated form of "railroad car") to refer to any item of hauled rolling-stock, whether passenger coaches or goods wagons (freight cars). Self-powered railcars were once common in North America; see Doodlebug (rail car).

In its simplest form, a "railcar" may also be little more than a motorized railway handcar or draisine.