Sullivan was born in Tustin, California, on February 9, 1981, of Irish descent. He received his first pair of drumsticks at the age of five and his own drum set at the age of twelve. In high school, he started playing in bands. 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. At the age of 20, he recorded his first album with Avenged Sevenfold titled Sounding the Seventh Trumpet. His early influences included Frank Zappa and King Crimson. The Rev stated in an interview with Modern Drummer that he “was raised on that stuff as much as rock and metal.”

On December 28, 2009, The Rev was found unresponsive in his Huntington Beach home, and was later pronounced dead upon arrival to the hospital. Police ruled out foul play and noted that his death appeared to be from natural causes. An autopsy performed on December 30, 2009, was inconclusive, but toxicology results revealed to the public in June that he died from an overdose of oxycodone (Percocet), oxymorphone (a metabolite of oxycodone), diazepam (Valium), nordiazepam (a metabolite of diazepam), and alcohol. The coroner noted an enlarged heart as a “significant condition” that may have played a role in Sullivan’s death.

On January 6, 2010, a private funeral was held for Sullivan, who was then buried in The Good Shepherd Cemetery, in Huntington Beach, California. Shortly after his death, Avenged Sevenfold dedicated their fifth studio album Nightmare (released that same year) to him, as well as several songs, including “So Far Away”, which had been written by bandmate (and childhood friend) Synyster Gates, and “Fiction”, which The Rev had written three days before his death. M. Shadows and Gates stated in an interview to Hard Drive Radio:

In an Ultimate Guitar online readers’ poll of the “Top Ten Greatest Drummers of All Time”, The Rev appeared at No. 8, placing higher than Bill Ward of Black Sabbath, and lower than Keith Moon of The Who. In 2017, he once again appeared in Ultimate Guitar’s list of Top 25 Greatest Singing Drummers, at No. 5.