The 4C System is a free core rules system created by Phil Reed and Michael Hammes of Ronin Arts. It uses percentile dice and a Master Table to determine task resolution outcomes and it's particularly suited to superheroic games.

The 4C System was developed as a free and open emulator of a popular roleplaying game system of marvelous superheroics available in the 1980's. The original system, known by many as FASERIP (an acronym of the main attributes of a character in the game), went out of print and was never picked up for a revival.

Though there is a healthy community of followers for that game online, aside from fan-made material, no further products could be developed due to copyright issues. The 4C System was designed to be fully compatible with the original system; using new terminology to express similar rules concepts, the 4C System manages to be an original work and a perfect emulator of the old and beloved game. This compatibility allows designers to create new material for both commercial and free distribution.