Aaron Roderick Gillespie is an American musician, best known for being the original and current drummer and clean vocalist for the rock band Underoath and the lead singer and rhythm guitarist for the alternative rock band the Almost. He has also worked with the band The Dangerous Summer. Gillespie also maintains his own solo project and released his debut full-length album, Anthem Song, in 2011. From 2013 to 2016, he was the touring drummer for Paramore.

Underoath is an American rock band from Tampa, Florida. It was founded by lead vocalist Dallas Taylor and guitarist Luke Morton in 1997 in Ocala, Florida; subsequently, its additional members were from Tampa, including drummer, clean vocalist and last remaining core member Aaron Gillespie. The band's current lineup consists of Gillespie, keyboardist Christopher Dudley, lead guitarist Timothy McTague, bassist Grant Brandell, and lead vocalist Spencer Chamberlain. Originally, the band identified as a Christian group; they have since distanced themselves from Christianity.