Generally speaking, a metallophone is any musical instrument consisting of tuned metal bars which are struck to make sound, usually with a mallet.

Metallophones have been used in music for hundreds of years. There are several different types used in Balinese and Javanese gamelan ensembles, including the gendér and saron . These instruments have a single row of bars, and are often tuned to a pentatonic scale. The glockenspiel and vibraphone are also metallophones - these have two rows of bars and are tuned to the chromatic scale.

In music of the 20th century and beyond, the word metallophone is sometimes applied specifically to a single row of metal bars suspended over a resonator box. Metallophones tuned to the diatonic scale are often used in schools; Carl Orff used diatonic metallophones in several of his pieces, including his pedagogical Schulwerk. Metallophones with microtonal tunings are used in Iannis Xenakis' Pléïades and in the music of Harry Partch.