The Rainmaker is the main antagonist in Looper, and while his presence throughout the movie is largely implied, there's still quite a lot of information revealed about him. The Rainmaker himself is technically never shown, which contributes immeasurably to his mystique and intimidation factor. Instead of a face-to-face altercation, what results between the Rainmaker and the other Looper characters is more akin to a chess match through time. The mind-bending adventure is made even more compelling by having such an enigmatic villain.

https://screenrant.com/looper-the-rainmaker-identity-powers-explained/