Justin Marler (born July 29, 1972) is an American musician. He is known for being a founding member of the stoner rock band Sleep and for leaving a burgeoning career in music to become a monk in an Eastern Orthodox monastery. In 1990, Marler joined the members of a little-known band called Asbestosdeath (with Al Cisneros, Chris Hakius and Matt Pike), which the members later renamed Sleep. Soon after recording Sleep's first full-length record, Volume One, Marler vanished, while the band went on to become metal icons.