What instruments are related to the theremin?

The theremin is related to several electronic instruments, including the Ondes Martenot, which also uses pitch control through hand movements and produces a similar eerie sound. Additionally, synthesizers, particularly those with voltage-controlled oscillators, share the theremin's electronic nature and can emulate its sound. Other related instruments include the Electro-Theremin, which uses a slide control to create pitch variations, and various MIDI controllers that allow for similar expressive performances.