Robert John Gaudio is an American singer, songwriter, musician, and record producer, best known mainly as the keyboardist and backing vocalist of the 1960s pop rock band The Four Seasons. Gaudio wrote or co-wrote the vast majority of the group's music, including hits like "Sherry" and "December, 1963 ", as well as "Can't Take My Eyes Off You" for Frankie Valli. Though he no longer performs with the band, Gaudio and lead singer Valli remain co-owners of "the Four Seasons" brand.