The Rev obtained his first pair of drum sticks at the age of four and received his own drum set at the age of eleven. 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 eighteen he recorded his first album with Avenged Sevenfold titled Sounding the Seventh Trumpet. His early influences included Frank Zappa and King Crimson. The Rev said in a Modern Drummer Magazine interview that "I was raised on that stuff as much as rock and metal."
Later in life he was influenced by drummers Vinnie Paul, Mike Portnoy, Dave Lombardo, Lars Ulrich, and Terry Bozzio. He even had a "visual influence", Tommy Lee, on which he commented that "I never thought I'd have one of those." Sullivan's signature ability which he called "the double-ride thing, just for lack of a better definition, because no one does it," is a technique that can be heard on tracks such as "Almost Easy", "Critical Acclaim", and "Crossroads" in which Sullivan doubles up at a fast tempo between the double bass and ride cymbals. As of late, current touring drummer, Arin Ilejay, has been doing the "double-ride thing" during live performances, which Mike Portnoy refused to do during his run with the band out of respect for The Rev.
The Rev was also a vocalist, songwriter, and pianist for Avenged Sevenfold. His piano-playing can be heard on the tracks "Warmness on the Soul", "Seize the Day", "Fiction" and "Save Me". His vocals are featured in Avenged Sevenfold's "A Little Piece of Heaven", "Brompton Cocktail", "Critical Acclaim", "Crossroads", "Gunslinger", "Lost", "Scream", "Afterlife", "Save Me", and "Fiction". He used his knowledge of the guitar and piano to write the songs "Almost Easy", "A Little Piece of Heaven", "Afterlife", "Brompton Cocktail", "Welcome to the Family", "Save Me", and "Fiction". He also contributed to the making of "Critical Acclaim" and "Lost".
Avenged Sevenfold also announced that they will be releasing a demo version of "Nightmare" including The Rev on an electric drumset and his vocals.
At the second annual Revolver Golden God Awards, The Rev won the award for Best Drummer beating out Chris Adler of Lamb of God, Brann Dailor of Mastodon, Dave Grohl of Them Crooked Vultures and Dave Lombardo of Slayer. The award was presented by Joey Jordison of Slipknot and Vinnie Paul of Pantera, with the latter winning the award the previous year. His family members and Avenged Sevenfold received the honor on his behalf.
Sullivan's body was found in his home on December 28, 2009 at the age of 28. His death was reported as due to natural causes. The results of the autopsy performed on December 30, 2009, however, were inconclusive. On June 9, 2010, the cause of death was revealed to have been an acute polydrug intoxication due to combined effects of oxycodone (OxyContin), oxymorphone (a metabolite of oxycodone), diazepam (Valium), nordiazepam (a metabolite of diazepam) and alcohol. Cardiomegaly(enlarged heart) was reported as a "significant condition" that may have played a role in the death.
Sullivan used Drum Workshop drums and hardware and Pro-Mark drumsticks. He was also seen using Ahead drumsticks in the recording of Avenged Sevenfold's self titled album. In the studio he used Sabian andZildjian cymbals, while he only used Sabians live.
Sizes and specs of drums: 8"x5" tom (not in use on tour) 8"x7" tom 10"x8" tom 12"x9" tom 14"x11" tom 16"x14" tom 18"x16" tom 22"x18" bass drum (x3) 14"x5" snare with chrome hardware and a 14"x6.5" DW bronze metal snare drum series with black hardware Evans heads on all.
Pedals: DW 9000 series (x2, third bass drum was for show)
Cymbals: 14" AAX-Celerator Hi-hats, 18" Sabian Signature Jojo Mayer Fierce Crash, 19" Paragon China, 19" AAX Metal Crash, 22" AAX Metal Ride (x2), 19"AAXtreme Chinese, 10" AAX Splash, 10" Chopper Effects Cymbal, 11" Signature Max Splash, 10" HH China Kang,
In the studio for the last self-titled album, The Rev used also Zildjian cymbals: he used an 18" Oriental Classic China instead of the Paragon, two 21" Zildjian Z-Custom Mega Bell Rides instead of the AAX Metal Rides and an A-Custom Projection Crash instead of the AAX Metal Crashes.