Roy Marcus Cohn was an American lawyer and prosecutor. He first gained fame as a prosecutor of Julius and Ethel Rosenberg in their trials and as Senator Joseph McCarthy's chief counsel during the Army–McCarthy hearings in 1954. From Wikipedia
Hulu’s Tell Me Everything exposes Walters’s strategic partnerships with controversial figures such as Roy Cohn; its archival interviews reveal her competitive tensions with Diane Sawyer, complemented by Oprah Winfrey’s reflections.