The Mellotron is an electromechanical polyphonic keyboard musical instrument originally developed and built in Birmingham, England in the early 1960s.

The Mellotron, (along with its direct ancestor the Chamberlin), was in effect the world's first sample-playback keyboard. The heart of the instrument is a bank of parallel linear (not looped) strips of magnetic tape, each with approximately eight seconds of playing time; playback heads underneath (but not directly underneath) each key enable performers to play the pre-recorded sound assigned to that key when pressed. The earlier MK. I, and MK. II models contained two side-by-side keyboards with 18 selectable sets of specially-recorded sounds on the right keyboard such as strings, flutes, and brass instruments which were called "lead", or "instrument" sounds, and pre-recorded accompaniment music (in various styles) on the left keyboard. The tape banks for the later, and lighter M.400 models contain three selectable sounds (per changeable tape-rack) such as strings, cello, and the famous eight-voice choir. The sound on each individual tape piece is recorded at the specific pitch of the key that it was assigned to.