- "Without the midi-chlorians, life could not exist, and we would have no knowledge of the Force. They continually speak to us, telling us the will of the Force. When you learn to quiet your mind, you'll hear them speaking to you."
- ―Qui-Gon Jinn, to Anakin Skywalker
Midi-chlorians were microscopic, intelligent lifeforms that live within the cells of all living beings. The Force spoke through the midi-chlorians, allowing certain beings to use the Force if they were sensitive enough to its powers. Midi-chlorian counts, used to determine a being's potential in the Force, could be tested by examining a subject's blood. The highest known midi-chlorian count—over 20,000—belonged to Anakin Skywalker, the Chosen One who was believed to have been conceived by the midi-chlorians.
According to legend, midi-chlorians originated on a planet in the heart of the galaxy, from which life was also said to have emerged. The midi-chlorians played a role in eternal consciousness; as all living beings generated the Living Force, it fed into the Cosmic Force and communicated through the midi-chlorians, allowing a being who had the knowledge to manifest themselves after death.
- Star Wars: Episode I The Phantom Menace (First mentioned)
- Star Wars: The Clone Wars – "Deception" (Mentioned only)
- Star Wars: The Clone Wars – "Voices" (Mentioned only)
- Star Wars: The Clone Wars – "Destiny" (Mentioned only)
- Star Wars: Episode III Revenge of the Sith (Mentioned only)