Francesco Stephen Castelluccio, better known by his stage name Frankie Valli, is an American singer, best known as the frontman of the Four Seasons beginning in 1960. He is known for his unusually powerful lead falsetto voice.

Charles Calello is an American arranger, composer, conductor, record producer, and singer born in Newark, New Jersey. Calello attended Newark Arts High School and the Manhattan School of Music, in New York City. His track record of successfully collaborating with various artists to produce or arrange Billboard hit songs led to his nickname in the industry as the "Hit Man."