The West Side Story composer is Leonard Bernstein, a 9-letter name. Bernstein was an American composer, conductor, author, music lecturer, and pianist. He was one of the first conductors born and educated in the United States of America to receive worldwide acclaim. He is best known for his compositions for West Side Story, On the Town, Candide, and Wonderful Town. Bernstein also wrote symphonies, ballets, and other works for the concert stage.