JeanMilius · CC BY-SA 4.0

A screenwriter and director whose scripts for Dirty Harry, Jeremiah Johnson, and Apocalypse Now (with an Academy Award nomination for the last) helped define 1970s New Hollywood, before he moved into directing action films himself with Conan the Barbarian (1982) and Red Dawn (1984). He was also a driving force behind the creation of the Ultimate Fighting Championship, helping design its octagonal cage and bring in early investors.