The Holophonor is a musical instrument of the 30th Century, it is best described as a combination of an Oboe and a Holographic Projector.
The notes played by its user triggers the projector to show holographic images which relate to the mood of the notes. Due to its complicated nature, it requires a great amount of skill to play. According to Leela, only a few people possess the skill to play the instrument - and they are not very good at it.
In Parasites Lost a clan of parasitic worms improve Fry and enable him to play the Holophonor to perfection, which he uses to win Leela's heart. Once he rids his body of the worms his skill becomes nothing more than that of a beginner and Leela dumps him.
Fry tried in vain to regain his skill with the instrument until he makes a deal with the Robot Devil in which he gains his robotic hands and begins to write an opera inspired by Leela which he partially performs in front of a sellout audience before The Robot Devil retakes possession of his robotic hands.
- According to the commentary for Parasites Lost, the holophoner is based on Visi-Sonor from the Foundation Trilogy. A similiar idea was used by Samuel R. Delaney in his novel 'Nova'.