Leonard Bernstein’s melody is interpolated in the introduction to Metallica's “Don't Tread on Me” from The Black Album.
The opening uses a brief passage from “America,” a melody Bernstein composed for the musical West Side Story. Metallica placed that recognizable musical reference before the song’s heavy riff and lyrics, creating a deliberate contrast between orchestral theater music and hard rock.
“Don’t Tread on Me” also connects musically and visually to the album’s cover. Its title comes from the motto on the Gadsden flag, while the cover displays a coiled snake derived from that flag. The song’s subject and the artwork therefore reinforce one another.
The composer is sometimes confused with Stephen Sondheim, who wrote the lyrics for West Side Story. Bernstein composed the music, while Sondheim wrote the lyrics. For the melody used in Metallica’s introduction, the canonical answer is Leonard Bernstein.