Merle Colby Allin, Jr. (born September 1, 1953) is an American electric bass guitar player. He is the older brother of the late punk rock singer/songwriter GG Allin.
Allin played bass for three main groups that featured GG Allin: Malpractice, The AIDS Brigade and The Murder Junkies. He currently continues the Murder Junkies, his brother's last backing band, with original drummer Donald ("Dino Sex") Sachs, and a varying line-up of younger members.
Allin was also bass player in late 70's Boston punk group Thrills (a.k.a. City Thrills), who released several singles, and opened for acts such as David Johansen, the Cars, and the Ramones. He subsequently joined the band Cheater Slicks, and played bass guitar on their debut album, "On Your Knees." Allin's trademark is his overgrown toothbrush moustache.