Brett Gurewitz (born May 12, 1962A number of sources mistakenly list 1964 as his year of birth. See the article on age disputes and discrepancies for details., Los Angeles, California), nicknamed Mr. Brett, is the guitarist and a songwriter of Bad Religion. He is also the owner of the music label Epitaph Records. Brett grew up in the town of Woodland Hills, California, a suburb of L.A.'s San Fernando Valley.

He has produced albums for Bad Religion as well as Epitaph Records labelmates NOFX, Rancid, and Pennywise, among others. Gurewitz left Bad Religion after the 1983 release of the unpopular Into the Unknown album, but returned in 1986. He left again after the 1994 release of their highly acclaimed album Stranger Than Fiction and was replaced by Brian Baker. Gurewitz started a new band, Daredevils, but rejoined Bad Religion in 2001 before they recorded their 2002 comeback album The Process of Belief. He remains with the band today, but only occasionally joins them live, such as when they are performing near his hometown or for televised appearances.