Drummer Mark O'Connell joined Taking Back Sunday in 2001, brought in by his friend Eddie Reyes, the band’s founder. He has played drums on all seven of their studio albums.

O'Connell hits hard, particularly influencing TBS’s sound for their major labor debut in 2006, appropriately titled Louder Now. He told Drum!:

“I grew up in a hardcore scene. I grew up listening to metal. I can’t stand wimps behind the drums. I can’t stand light hitters … I just like banging the s**t out of my shells.”