Three-dimensional chess (or 3D chess) refers to any of various chess variants that use multiple boards representing different levels, allowing the chess pieces to "move" through all three physical dimensions. Three-dimensional variants have existed since the late 19th century, one of the oldest being Raumschach (German for "Space chess"), invented in 1907 by Dr. Ferdinand Maack and considered the classic 3D game. Maack founded a Raumschach club in Hamburg in 1919, which remained active until World War II.

Chapter 25 of Pritchard's The Classified Encyclopedia of Chess Variants discusses games using boards with three or more dimensions and contains some 50 such variations. In addition, chapter 11 covers variants using multiple boards normally set side by side ("such games can also be considered as examples of three-dimensional chess" — Beasley).

All the movements of orthodox Chess pieces as 3D Chess pieces is easily visualized by putting a chessboard on its side, or otherwise shifting it to represent any of the three planes. These diagrams of orthodox Chess piece moves are usually looked at top down, but they also can be looked at to represent the right/left side vertical movements or the front/back vertical movements in the two other planes.