Frankie Valli, born Francesco Stephen Castelluccio, is an American singer known for his distinctive falsetto vocals. He gained fame as the lead singer of The Four Seasons, a band that dominated the pop charts in the 1960s with hits like "Sherry", "Big Girls Don't Cry", and "Walk Like a Man". Valli's unique voice and the band's harmonic sound played a crucial role in shaping the doo-wop genre and influenced future pop music. Despite numerous lineup changes over the years, Valli remained a constant, solidifying his status as one of the enduring figures of American popular music.