Fictional entities existing in the Star Wars universe. They are microscopic and intelligent, and about 2,500 live in every cell of a regular human body.

Controversially, they are also responsible for people's ability to sense The Force. The concept of midi-chlorians was not canonically introduced to the Star Wars universe until 1999 in The Phantom Menace. Critics lamented their introduction, stating that they removed the mysticism that made The Force such an interesting concept. Midi-chlorians remain a source of controversy amongst fans even now, with many feeling like they were a completely unnecessary contrivance.