Born in Baltimore, Maryland, he produced and directed documentaries for National Geographic and David Wolper, including The Hellstrom Chronicle, for which he was accorded the Academy Award and the BAFTA in 1972, and The Secret Life of Plants in 1979. Among his screenwriting credits are the films The Wild Bunch, Sorcerer, The Brink's Job, Eraser, The Hi-Lo Country and RoboCop 2. On television he wrote and produced episodes of Hill Street Blues, Law & Order, ER and NYPD Blue for which he received a 1995 Edgar Award. More recently he was a Creative Consultant for the Chris Carter science fiction TV series Millennium. He is also notable for allowing a centipede to crawl over his face in the tunnel scene of Willy Wonka and the Chocolate Factory.

Green is the father of Darwin Green, a writer and film editor, and Collin Green, a teacher and photographer.

In fall 2008, he assumed the post of executive producer for the Vincent D'Onofrio-Kathryn Erbe episodes of Criminal Intent.

Bunker Hill: Bridget Moynahan ("Six Degrees") has joined the cast of the drama pilot, about a cop (Donnie Wahlberg) who returns to the Boston, MA neighborhood he grew up in. She'll play Erin, the sister-in-law of Wahlberg's character, who has a love-hate relationship with him stemming from the death of her cop husband. Walon Green (Head Writer/Showrunner) is behind the Warner Horizon Television-based hour, which Jon Avnet is attached to direct. [1], [2], [3], [4]