Brett W. Gurewitz, nicknamed Mr. Brett, is an American musician best known as the co-founder and lead guitarist of Bad Religion. He is also the owner of the music label Epitaph Records and a number of sister labels. He has produced albums for Bad Religion as well as Epitaph Records labelmates NOFX, Rancid, and Pennywise, among others. Gurewitz also had a project called Error, which also featured Atticus Ross, Leopold Ross, and Greg Puciato. He is also the co-founder of comic book and graphic novel publisher, Black Mask Studios.

Black Mask Studios is a comic book and graphic novel publishing company formed by Matt Pizzolo, Steve Niles and Brett Gurewitz, designed as a new infrastructure to support comic book creators and a new pipeline for transgressive art.