A flatcar is a piece of railway rolling stock that consists of an open, flat deck on four or six wheels or a pair of trucks. The deck of the car can be wood or steel, and the sides of the deck can include pockets for stakes or tie-down points to secure loads. Flatcars designed for carrying machinery have sliding chain assemblies recessed in the deck.

Flatcars are used for loads that are too large or cumbersome to load in enclosed cars such as boxcars. They are also often used to transport intermodal containers (shipping containers) or trailers as part of intermodal freight transport shipping.