The Theremin is an early electronic musical instrument controlled without contact from the player. It is named after its Russian inventor, Professor Léon Theremin, who patented the device in 1928.
Theremin demonstrated the device to Bolshevik leader Vladimir Lenin. Lenin was so impressed he began taking lessons in playing it.
The theremin is associated with a very eerie sound, which has led to its use in movie soundtracks such as Spellbound, one of my favorite films.