Monotron (stylised as monotron in all lowercase) is the collective name of a series of miniature monophonic analogue synthesisers produced by Korg, a Japanese manufacturer of electronic musical instruments. There are three models in the series: the original Monotron (released 2010), the Monotron Duo (released 2011) and the Monotron Delay (released 2011). The models share a minimalist set of synthesis components, consisting only of a voltage-controlled oscillator, voltage-controlled filter, a voltage-controlled amplifier and a low-frequency oscillator.
Critics received the Monotron series well, citing the synthesisers' analogue circuits, which were a novelty at the time. The Monotrons proved successful with consumers, especially with electronics hobbyists, who made modifications to the synthesisers' designs. Korg did not originally intend for the Monotrons to be used for this purpose: rather, it was a consequence of the company labeling the synthesisers' PCB solder points and publicly releasing their schematics.
The Monotron played a role in an "analogue revival" of synthesisers by showing that analogue synthesisers could still be popular in the digital era. Korg's decision to release the Monotron in 2010 emboldened other manufacturers to produce their own offerings, making analogue synthesisers popular again. Korg continued to release other analogue offerings, such as the Monotribe (released in 2011).