NEW YORK - Nicholas deB. Katzenbach, who helped shape the political history of the 1960s, facing down segregationists, riding herd on historic civil rights legislation, and helping to map Vietnam War strategy as a central player in both the Kennedy and Johnson administrations, died Tuesday night at his home in Skillman, N.J. He was 90.

His death was confirmed by his wife, Lydia.

Mr. Katzenbach was one of the “best and the brightest,’’ David Halberstam’s term for the likes of Robert McNamara, McGeorge Bundy, Walt Rostow, and other ambitious, cerebral and often idealistic postwar policy makers who came to Washington from business and academia carrying golden credentials. Mr. Katzenbach, an attorney general under President Lyndon B. Johnson, was the son of a New Jersey state attorney general, a Rhodes scholar, a law professor at Yale and the University of Chicago, and a war hero.

His government service virtually encompassed the issues of the ’60s. He advised President John F. Kennedy during the Cuban missile crisis, negotiated the release of Cuban prisoners captured during the Bay of Pigs invasion, and pushed for an independent commission to investigate the Kennedy assassination. He was Robert F. Kennedy’s top lieutenant in the Justice Department and took on the pugnacious FBI director J. Edgar Hoover over his wiretapping of the Rev. Dr. Martin Luther King Jr. Before Congress, as an undersecretary of state, he defended Johnson’s escalation of the Vietnam War.

Perhaps his most tense moment in government came on June 11, 1963, when he confronted George C. Wallace in stifling heat on the steps of the University of Alabama in Tuscaloosa. Wallace was the Alabama governor who had trumpeted “segregation now, segregation tomorrow, segregation forever’’ and vowed to block the admission of two black students “at the schoolhouse door.’’