Derek Shawn O'Brien (Fullerton, California) is a drummer and producer / engineer who has been involved with many bands and projects throughout his career.
He started his career while still at Fullerton High School (playing with the school Jazz Band, Marching Band and Orchestras led by Ron Perry) and played in Rock cover bands by night with Guitarists Stan De Witt and Frank Agnew. While still in High School, he joined local punk rock band Social Distortion and was considered to be the group's first real and consistent drummer. (1981–1984). His recordings with the band include the first EP "1945", Single ("Playpen"), BYO Compilation song "(Mass Hysteria)", and first full length album Mommy's Little Monster. He was also featured in the cult classic Documentary "Another State Of Mind".
O'Brien was also involved in D.I. (which also featured many former members of Social Distortion and The Adolescents) and played on their 1983 EP Team Goon (which used to be known as simply D.I.) and performed in the film Suburbia.