His early influences included Frank Zappa and King Crimson. At the age of 20, he recorded his first album with Avenged Sevenfold titled Sounding the Seventh Trumpet. Before leaving to join Avenged Sevenfold as one of the band's founding members, Sullivan was the drummer for the third wave ska band Suburban Legends. In high school, he started playing in bands.
He received his first pair of drumsticks at the age of five and his own drum set at the age of twelve. Sullivan was born on February 9, 1981, of Irish descent and raised Roman Catholic.
