Legendary “ Saturday Night Live ” writer Jim Downey is the subject of a new documentary coming to Peacock on Oct. 17. Titled “Downey Wrote That,” the hour-long film will highlight the sketches, comedic voice and enduring influence of the longest-running writer in the history of “SNL.” Downey joined the show in its second season in 1976 and wrote for 30 seasons across four stints at Studio 8H. He is known as the “behind-the-scenes comedic architect” of the “SNL,” who wrote some of the show’s